| Message ID | 20190801021752.4986-5-david@fromorbit.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm, xfs: non-blocking inode reclaim | expand |
On Thu, Aug 01, 2019 at 12:17:32PM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > Right now deferred work is picked up by whatever GFP_KERNEL context > reclaimer that wins the race to empty the node's deferred work > counter. However, if there are lots of direct reclaimers, that > work might be continually picked up by contexts taht can't do any > work and so the opportunities to do the work are missed by contexts > that could do them. > > A further problem with the current code is that the deferred work > can be picked up by a random direct reclaimer, resulting in that > specific process having to do all the deferred reclaim work and > hence can take extremely long latencies if the reclaim work blocks > regularly. This is not good for direct reclaim fairness or for > minimising long tail latency events. > > To avoid these problems, simply limit deferred work to kswapd > contexts. We know kswapd is a context that can always do reclaim > work, and hence deferring work to kswapd allows the deferred work to > be done in the background and not adversely affect any specific > process context doing direct reclaim. > > The advantage of this is that amount of work to be done in direct > reclaim is now bound and predictable - it is entirely based on > the cache's freeable objects and the reclaim priority. hence all > direct reclaimers running at the same time should be doing > relatively equal amounts of work, thereby reducing the incidence of > long tail latencies due to uneven reclaim workloads. > > Signed-off-by: Dave Chinner <dchinner@redhat.com> > --- > mm/vmscan.c | 93 ++++++++++++++++++++++++++++------------------------- > 1 file changed, 50 insertions(+), 43 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index b7472953b0e6..c583b4efb9bf 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -500,15 +500,15 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > struct shrinker *shrinker, int priority) > { > unsigned long freed = 0; > - long total_scan; > int64_t freeable_objects = 0; > int64_t scan_count; > - long nr; > + int64_t scanned_objects = 0; > + int64_t next_deferred = 0; > + int64_t deferred_count = 0; > long new_nr; > int nid = shrinkctl->nid; > long batch_size = shrinker->batch ? shrinker->batch > : SHRINK_BATCH; > - long scanned = 0, next_deferred; > > if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > nid = 0; > @@ -519,47 +519,53 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > return scan_count; > > /* > - * copy the current shrinker scan count into a local variable > - * and zero it so that other concurrent shrinker invocations > - * don't also do this scanning work. > + * If kswapd, we take all the deferred work and do it here. We don't let > + * direct reclaim do this, because then it means some poor sod is going > + * to have to do somebody else's GFP_NOFS reclaim, and it hides the real > + * amount of reclaim work from concurrent kswapd operations. Hence we do > + * the work in the wrong place, at the wrong time, and it's largely > + * unpredictable. > + * > + * By doing the deferred work only in kswapd, we can schedule the work > + * according the the reclaim priority - low priority reclaim will do > + * less deferred work, hence we'll do more of the deferred work the more > + * desperate we become for free memory. This avoids the need for needing > + * to specifically avoid deferred work windup as low amount os memory > + * pressure won't excessive trim caches anymore. > */ > - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > + if (current_is_kswapd()) { > + int64_t deferred_scan; > > - total_scan = nr + scan_count; > - if (total_scan < 0) { > - pr_err("shrink_slab: %pS negative objects to delete nr=%ld\n", > - shrinker->scan_objects, total_scan); > - total_scan = scan_count; > - next_deferred = nr; > - } else > - next_deferred = total_scan; > + deferred_count = atomic64_xchg(&shrinker->nr_deferred[nid], 0); > > - /* > - * We need to avoid excessive windup on filesystem shrinkers > - * due to large numbers of GFP_NOFS allocations causing the > - * shrinkers to return -1 all the time. This results in a large > - * nr being built up so when a shrink that can do some work > - * comes along it empties the entire cache due to nr >>> > - * freeable. This is bad for sustaining a working set in > - * memory. > - * > - * Hence only allow the shrinker to scan the entire cache when > - * a large delta change is calculated directly. > - */ > - if (scan_count < freeable_objects / 4) > - total_scan = min_t(long, total_scan, freeable_objects / 2); > + /* we want to scan 5-10% of the deferred work here at minimum */ > + deferred_scan = deferred_count; > + if (priority) > + do_div(deferred_scan, priority); > + scan_count += deferred_scan; > + > + /* > + * If there is more deferred work than the number of freeable > + * items in the cache, limit the amount of work we will carry > + * over to the next kswapd run on this cache. This prevents > + * deferred work windup. > + */ > + if (deferred_count > freeable_objects * 2) > + deferred_count = freeable_objects * 2; > + Hmm, what's the purpose of this check? Is this not handled once the deferred count is absorbed into scan_count (where we apply the same logic a few lines below)? Perhaps the latter prevents too much scanning in a single call into the shrinker whereas this check prevents kswapd from getting too far behind? > + } > > /* > * Avoid risking looping forever due to too large nr value: > * never try to free more than twice the estimate number of > * freeable entries. > */ > - if (total_scan > freeable_objects * 2) > - total_scan = freeable_objects * 2; > + if (scan_count > freeable_objects * 2) > + scan_count = freeable_objects * 2; > > - trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, > + trace_mm_shrink_slab_start(shrinker, shrinkctl, deferred_count, > freeable_objects, scan_count, > - total_scan, priority); > + scan_count, priority); > > /* > * If the shrinker can't run (e.g. due to gfp_mask constraints), then > @@ -583,10 +589,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > * scanning at high prio and therefore should try to reclaim as much as > * possible. > */ > - while (total_scan >= batch_size || > - total_scan >= freeable_objects) { > + while (scan_count >= batch_size || > + scan_count >= freeable_objects) { > unsigned long ret; > - unsigned long nr_to_scan = min(batch_size, total_scan); > + unsigned long nr_to_scan = min_t(long, batch_size, scan_count); > > shrinkctl->nr_to_scan = nr_to_scan; > shrinkctl->nr_scanned = nr_to_scan; > @@ -596,17 +602,17 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > freed += ret; > > count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); > - total_scan -= shrinkctl->nr_scanned; > - scanned += shrinkctl->nr_scanned; > + scan_count -= shrinkctl->nr_scanned; > + scanned_objects += shrinkctl->nr_scanned; > > cond_resched(); > } > > done: > - if (next_deferred >= scanned) > - next_deferred -= scanned; > - else > - next_deferred = 0; > + if (deferred_count) > + next_deferred = deferred_count - scanned_objects; > + else if (scan_count > 0) > + next_deferred = scan_count; I was wondering why we dropped the >= scanned_objects check, but I see that next_deferred is signed and we check for next_deferred > 0 below. What is odd is that so is scan_count, yet we check > 0 here for assignment to the same variable. Can we be a little more consistent here one way or the other? Brian > /* > * move the unused scan count back into the shrinker in a > * manner that handles concurrent updates. If we exhausted the > @@ -618,7 +624,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > else > new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); > > - trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); > + trace_mm_shrink_slab_end(shrinker, nid, freed, deferred_count, new_nr, > + scan_count); > return freed; > } > > -- > 2.22.0 >
On 1.08.19 г. 5:17 ч., Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > Right now deferred work is picked up by whatever GFP_KERNEL context > reclaimer that wins the race to empty the node's deferred work > counter. However, if there are lots of direct reclaimers, that > work might be continually picked up by contexts taht can't do any > work and so the opportunities to do the work are missed by contexts > that could do them. > > A further problem with the current code is that the deferred work > can be picked up by a random direct reclaimer, resulting in that > specific process having to do all the deferred reclaim work and > hence can take extremely long latencies if the reclaim work blocks > regularly. This is not good for direct reclaim fairness or for > minimising long tail latency events. > > To avoid these problems, simply limit deferred work to kswapd > contexts. We know kswapd is a context that can always do reclaim > work, and hence deferring work to kswapd allows the deferred work to > be done in the background and not adversely affect any specific > process context doing direct reclaim. > > The advantage of this is that amount of work to be done in direct > reclaim is now bound and predictable - it is entirely based on > the cache's freeable objects and the reclaim priority. hence all > direct reclaimers running at the same time should be doing > relatively equal amounts of work, thereby reducing the incidence of > long tail latencies due to uneven reclaim workloads. > > Signed-off-by: Dave Chinner <dchinner@redhat.com> > --- > mm/vmscan.c | 93 ++++++++++++++++++++++++++++------------------------- > 1 file changed, 50 insertions(+), 43 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index b7472953b0e6..c583b4efb9bf 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -500,15 +500,15 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > struct shrinker *shrinker, int priority) > { > unsigned long freed = 0; > - long total_scan; > int64_t freeable_objects = 0; > int64_t scan_count; > - long nr; > + int64_t scanned_objects = 0; > + int64_t next_deferred = 0; > + int64_t deferred_count = 0; > long new_nr; > int nid = shrinkctl->nid; > long batch_size = shrinker->batch ? shrinker->batch > : SHRINK_BATCH; > - long scanned = 0, next_deferred; > > if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > nid = 0; > @@ -519,47 +519,53 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > return scan_count; > > /* > - * copy the current shrinker scan count into a local variable > - * and zero it so that other concurrent shrinker invocations > - * don't also do this scanning work. > + * If kswapd, we take all the deferred work and do it here. We don't let > + * direct reclaim do this, because then it means some poor sod is going > + * to have to do somebody else's GFP_NOFS reclaim, and it hides the real > + * amount of reclaim work from concurrent kswapd operations. Hence we do > + * the work in the wrong place, at the wrong time, and it's largely > + * unpredictable. > + * > + * By doing the deferred work only in kswapd, we can schedule the work > + * according the the reclaim priority - low priority reclaim will do > + * less deferred work, hence we'll do more of the deferred work the more > + * desperate we become for free memory. This avoids the need for needing > + * to specifically avoid deferred work windup as low amount os memory > + * pressure won't excessive trim caches anymore. > */ > - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > + if (current_is_kswapd()) { > + int64_t deferred_scan; > > - total_scan = nr + scan_count; > - if (total_scan < 0) { > - pr_err("shrink_slab: %pS negative objects to delete nr=%ld\n", > - shrinker->scan_objects, total_scan); > - total_scan = scan_count; > - next_deferred = nr; > - } else > - next_deferred = total_scan; > + deferred_count = atomic64_xchg(&shrinker->nr_deferred[nid], 0); > > - /* > - * We need to avoid excessive windup on filesystem shrinkers > - * due to large numbers of GFP_NOFS allocations causing the > - * shrinkers to return -1 all the time. This results in a large > - * nr being built up so when a shrink that can do some work > - * comes along it empties the entire cache due to nr >>> > - * freeable. This is bad for sustaining a working set in > - * memory. > - * > - * Hence only allow the shrinker to scan the entire cache when > - * a large delta change is calculated directly. > - */ > - if (scan_count < freeable_objects / 4) > - total_scan = min_t(long, total_scan, freeable_objects / 2); > + /* we want to scan 5-10% of the deferred work here at minimum */ > + deferred_scan = deferred_count; > + if (priority) > + do_div(deferred_scan, priority); > + scan_count += deferred_scan; > + > + /* > + * If there is more deferred work than the number of freeable > + * items in the cache, limit the amount of work we will carry > + * over to the next kswapd run on this cache. This prevents > + * deferred work windup. > + */ > + if (deferred_count > freeable_objects * 2) > + deferred_count = freeable_objects * 2; nit : deferred_count = min(deferred_count, freeable_objects * 2). How can we have more deferred objects than are currently on the LRU? Aren't deferred objects always some part of freeable objects. Shouldn't this mean that for a particular shrinker deferred_count <= freeable_objects? > + > + } > > /* > * Avoid risking looping forever due to too large nr value: > * never try to free more than twice the estimate number of > * freeable entries. > */ > - if (total_scan > freeable_objects * 2) > - total_scan = freeable_objects * 2; > + if (scan_count > freeable_objects * 2) > + scan_count = freeable_objects * 2; nit: scan_count = min(scan_count, freeable_objects * 2); > > - trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, > + trace_mm_shrink_slab_start(shrinker, shrinkctl, deferred_count, > freeable_objects, scan_count, > - total_scan, priority); > + scan_count, priority); > > /* > * If the shrinker can't run (e.g. due to gfp_mask constraints), then > @@ -583,10 +589,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > * scanning at high prio and therefore should try to reclaim as much as > * possible. > */ > - while (total_scan >= batch_size || > - total_scan >= freeable_objects) { > + while (scan_count >= batch_size || > + scan_count >= freeable_objects) { > unsigned long ret; > - unsigned long nr_to_scan = min(batch_size, total_scan); > + unsigned long nr_to_scan = min_t(long, batch_size, scan_count); > > shrinkctl->nr_to_scan = nr_to_scan; > shrinkctl->nr_scanned = nr_to_scan; > @@ -596,17 +602,17 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > freed += ret; > > count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); > - total_scan -= shrinkctl->nr_scanned; > - scanned += shrinkctl->nr_scanned; > + scan_count -= shrinkctl->nr_scanned; > + scanned_objects += shrinkctl->nr_scanned; > > cond_resched(); > } > > done: > - if (next_deferred >= scanned) > - next_deferred -= scanned; > - else > - next_deferred = 0; > + if (deferred_count) > + next_deferred = deferred_count - scanned_objects; > + else if (scan_count > 0) > + next_deferred = scan_count; > /* > * move the unused scan count back into the shrinker in a > * manner that handles concurrent updates. If we exhausted the > @@ -618,7 +624,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > else > new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); > > - trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); > + trace_mm_shrink_slab_end(shrinker, nid, freed, deferred_count, new_nr, > + scan_count); > return freed; > } > >
On Sun, Aug 04, 2019 at 07:48:01PM +0300, Nikolay Borisov wrote: > > > On 1.08.19 г. 5:17 ч., Dave Chinner wrote: > > From: Dave Chinner <dchinner@redhat.com> > > > > Right now deferred work is picked up by whatever GFP_KERNEL context > > reclaimer that wins the race to empty the node's deferred work > > counter. However, if there are lots of direct reclaimers, that > > work might be continually picked up by contexts taht can't do any > > work and so the opportunities to do the work are missed by contexts > > that could do them. > > > > A further problem with the current code is that the deferred work > > can be picked up by a random direct reclaimer, resulting in that > > specific process having to do all the deferred reclaim work and > > hence can take extremely long latencies if the reclaim work blocks > > regularly. This is not good for direct reclaim fairness or for > > minimising long tail latency events. > > > > To avoid these problems, simply limit deferred work to kswapd > > contexts. We know kswapd is a context that can always do reclaim > > work, and hence deferring work to kswapd allows the deferred work to > > be done in the background and not adversely affect any specific > > process context doing direct reclaim. > > > > The advantage of this is that amount of work to be done in direct > > reclaim is now bound and predictable - it is entirely based on > > the cache's freeable objects and the reclaim priority. hence all > > direct reclaimers running at the same time should be doing > > relatively equal amounts of work, thereby reducing the incidence of > > long tail latencies due to uneven reclaim workloads. > > > > Signed-off-by: Dave Chinner <dchinner@redhat.com> > > --- > > mm/vmscan.c | 93 ++++++++++++++++++++++++++++------------------------- > > 1 file changed, 50 insertions(+), 43 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index b7472953b0e6..c583b4efb9bf 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -500,15 +500,15 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > > struct shrinker *shrinker, int priority) > > { > > unsigned long freed = 0; > > - long total_scan; > > int64_t freeable_objects = 0; > > int64_t scan_count; > > - long nr; > > + int64_t scanned_objects = 0; > > + int64_t next_deferred = 0; > > + int64_t deferred_count = 0; > > long new_nr; > > int nid = shrinkctl->nid; > > long batch_size = shrinker->batch ? shrinker->batch > > : SHRINK_BATCH; > > - long scanned = 0, next_deferred; > > > > if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > > nid = 0; > > @@ -519,47 +519,53 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > > return scan_count; > > > > /* > > - * copy the current shrinker scan count into a local variable > > - * and zero it so that other concurrent shrinker invocations > > - * don't also do this scanning work. > > + * If kswapd, we take all the deferred work and do it here. We don't let > > + * direct reclaim do this, because then it means some poor sod is going > > + * to have to do somebody else's GFP_NOFS reclaim, and it hides the real > > + * amount of reclaim work from concurrent kswapd operations. Hence we do > > + * the work in the wrong place, at the wrong time, and it's largely > > + * unpredictable. > > + * > > + * By doing the deferred work only in kswapd, we can schedule the work > > + * according the the reclaim priority - low priority reclaim will do > > + * less deferred work, hence we'll do more of the deferred work the more > > + * desperate we become for free memory. This avoids the need for needing > > + * to specifically avoid deferred work windup as low amount os memory > > + * pressure won't excessive trim caches anymore. > > */ > > - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > > + if (current_is_kswapd()) { > > + int64_t deferred_scan; > > > > - total_scan = nr + scan_count; > > - if (total_scan < 0) { > > - pr_err("shrink_slab: %pS negative objects to delete nr=%ld\n", > > - shrinker->scan_objects, total_scan); > > - total_scan = scan_count; > > - next_deferred = nr; > > - } else > > - next_deferred = total_scan; > > + deferred_count = atomic64_xchg(&shrinker->nr_deferred[nid], 0); > > > > - /* > > - * We need to avoid excessive windup on filesystem shrinkers > > - * due to large numbers of GFP_NOFS allocations causing the > > - * shrinkers to return -1 all the time. This results in a large > > - * nr being built up so when a shrink that can do some work > > - * comes along it empties the entire cache due to nr >>> > > - * freeable. This is bad for sustaining a working set in > > - * memory. > > - * > > - * Hence only allow the shrinker to scan the entire cache when > > - * a large delta change is calculated directly. > > - */ > > - if (scan_count < freeable_objects / 4) > > - total_scan = min_t(long, total_scan, freeable_objects / 2); > > + /* we want to scan 5-10% of the deferred work here at minimum */ > > + deferred_scan = deferred_count; > > + if (priority) > > + do_div(deferred_scan, priority); > > + scan_count += deferred_scan; > > + > > + /* > > + * If there is more deferred work than the number of freeable > > + * items in the cache, limit the amount of work we will carry > > + * over to the next kswapd run on this cache. This prevents > > + * deferred work windup. > > + */ > > + if (deferred_count > freeable_objects * 2) > > + deferred_count = freeable_objects * 2; > > nit : deferred_count = min(deferred_count, freeable_objects * 2). *nod* > How can we have more deferred objects than are currently on the LRU? deferred work is aggregated. Put enough direct reclaimers in action in GFP_NOFS context (e.g. fsmark create workload) and it will wind up the deferred count much faster than kswapd can drain it. > Aren't deferred objects always some part of freeable objects. For a single scan, yes. In aggregate, no. Cheers, Dave.
diff --git a/mm/vmscan.c b/mm/vmscan.c index b7472953b0e6..c583b4efb9bf 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -500,15 +500,15 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, struct shrinker *shrinker, int priority) { unsigned long freed = 0; - long total_scan; int64_t freeable_objects = 0; int64_t scan_count; - long nr; + int64_t scanned_objects = 0; + int64_t next_deferred = 0; + int64_t deferred_count = 0; long new_nr; int nid = shrinkctl->nid; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; - long scanned = 0, next_deferred; if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) nid = 0; @@ -519,47 +519,53 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, return scan_count; /* - * copy the current shrinker scan count into a local variable - * and zero it so that other concurrent shrinker invocations - * don't also do this scanning work. + * If kswapd, we take all the deferred work and do it here. We don't let + * direct reclaim do this, because then it means some poor sod is going + * to have to do somebody else's GFP_NOFS reclaim, and it hides the real + * amount of reclaim work from concurrent kswapd operations. Hence we do + * the work in the wrong place, at the wrong time, and it's largely + * unpredictable. + * + * By doing the deferred work only in kswapd, we can schedule the work + * according the the reclaim priority - low priority reclaim will do + * less deferred work, hence we'll do more of the deferred work the more + * desperate we become for free memory. This avoids the need for needing + * to specifically avoid deferred work windup as low amount os memory + * pressure won't excessive trim caches anymore. */ - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); + if (current_is_kswapd()) { + int64_t deferred_scan; - total_scan = nr + scan_count; - if (total_scan < 0) { - pr_err("shrink_slab: %pS negative objects to delete nr=%ld\n", - shrinker->scan_objects, total_scan); - total_scan = scan_count; - next_deferred = nr; - } else - next_deferred = total_scan; + deferred_count = atomic64_xchg(&shrinker->nr_deferred[nid], 0); - /* - * We need to avoid excessive windup on filesystem shrinkers - * due to large numbers of GFP_NOFS allocations causing the - * shrinkers to return -1 all the time. This results in a large - * nr being built up so when a shrink that can do some work - * comes along it empties the entire cache due to nr >>> - * freeable. This is bad for sustaining a working set in - * memory. - * - * Hence only allow the shrinker to scan the entire cache when - * a large delta change is calculated directly. - */ - if (scan_count < freeable_objects / 4) - total_scan = min_t(long, total_scan, freeable_objects / 2); + /* we want to scan 5-10% of the deferred work here at minimum */ + deferred_scan = deferred_count; + if (priority) + do_div(deferred_scan, priority); + scan_count += deferred_scan; + + /* + * If there is more deferred work than the number of freeable + * items in the cache, limit the amount of work we will carry + * over to the next kswapd run on this cache. This prevents + * deferred work windup. + */ + if (deferred_count > freeable_objects * 2) + deferred_count = freeable_objects * 2; + + } /* * Avoid risking looping forever due to too large nr value: * never try to free more than twice the estimate number of * freeable entries. */ - if (total_scan > freeable_objects * 2) - total_scan = freeable_objects * 2; + if (scan_count > freeable_objects * 2) + scan_count = freeable_objects * 2; - trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, + trace_mm_shrink_slab_start(shrinker, shrinkctl, deferred_count, freeable_objects, scan_count, - total_scan, priority); + scan_count, priority); /* * If the shrinker can't run (e.g. due to gfp_mask constraints), then @@ -583,10 +589,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, * scanning at high prio and therefore should try to reclaim as much as * possible. */ - while (total_scan >= batch_size || - total_scan >= freeable_objects) { + while (scan_count >= batch_size || + scan_count >= freeable_objects) { unsigned long ret; - unsigned long nr_to_scan = min(batch_size, total_scan); + unsigned long nr_to_scan = min_t(long, batch_size, scan_count); shrinkctl->nr_to_scan = nr_to_scan; shrinkctl->nr_scanned = nr_to_scan; @@ -596,17 +602,17 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, freed += ret; count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); - total_scan -= shrinkctl->nr_scanned; - scanned += shrinkctl->nr_scanned; + scan_count -= shrinkctl->nr_scanned; + scanned_objects += shrinkctl->nr_scanned; cond_resched(); } done: - if (next_deferred >= scanned) - next_deferred -= scanned; - else - next_deferred = 0; + if (deferred_count) + next_deferred = deferred_count - scanned_objects; + else if (scan_count > 0) + next_deferred = scan_count; /* * move the unused scan count back into the shrinker in a * manner that handles concurrent updates. If we exhausted the @@ -618,7 +624,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, else new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); - trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); + trace_mm_shrink_slab_end(shrinker, nid, freed, deferred_count, new_nr, + scan_count); return freed; }