| Message ID | 20190603210746.15800-6-hannes@cmpxchg.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: fix page aging across multiple cgroups | expand |
On Mon, Jun 3, 2019 at 3:05 PM Johannes Weiner <hannes@cmpxchg.org> wrote: > > Most of the function body is inside a loop, which imposes an > additional indentation and scoping level that makes the code a bit > hard to follow and modify. > > The looping only happens in case of reclaim-compaction, which isn't > the common case. So rather than adding yet another function level to > the reclaim path and have every reclaim invocation go through a level > that only exists for one specific cornercase, use a retry goto. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> > --- > mm/vmscan.c | 266 ++++++++++++++++++++++++++-------------------------- > 1 file changed, 133 insertions(+), 133 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index afd5e2432a8e..304974481146 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2672,164 +2672,164 @@ static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) > static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) > { > struct reclaim_state *reclaim_state = current->reclaim_state; > + struct mem_cgroup *root = sc->target_mem_cgroup; > + struct mem_cgroup_reclaim_cookie reclaim = { > + .pgdat = pgdat, > + .priority = sc->priority, > + }; > unsigned long nr_reclaimed, nr_scanned; > bool reclaimable = false; > + struct mem_cgroup *memcg; > > - do { > - struct mem_cgroup *root = sc->target_mem_cgroup; > - struct mem_cgroup_reclaim_cookie reclaim = { > - .pgdat = pgdat, > - .priority = sc->priority, > - }; > - struct mem_cgroup *memcg; > - > - memset(&sc->nr, 0, sizeof(sc->nr)); > +again: > + memset(&sc->nr, 0, sizeof(sc->nr)); > > - nr_reclaimed = sc->nr_reclaimed; > - nr_scanned = sc->nr_scanned; > + nr_reclaimed = sc->nr_reclaimed; > + nr_scanned = sc->nr_scanned; > > - memcg = mem_cgroup_iter(root, NULL, &reclaim); > - do { > - unsigned long reclaimed; > - unsigned long scanned; > + memcg = mem_cgroup_iter(root, NULL, &reclaim); > + do { > + unsigned long reclaimed; > + unsigned long scanned; > > - switch (mem_cgroup_protected(root, memcg)) { > - case MEMCG_PROT_MIN: > - /* > - * Hard protection. > - * If there is no reclaimable memory, OOM. > - */ > + switch (mem_cgroup_protected(root, memcg)) { > + case MEMCG_PROT_MIN: > + /* > + * Hard protection. > + * If there is no reclaimable memory, OOM. > + */ > + continue; > + case MEMCG_PROT_LOW: > + /* > + * Soft protection. > + * Respect the protection only as long as > + * there is an unprotected supply > + * of reclaimable memory from other cgroups. > + */ > + if (!sc->memcg_low_reclaim) { > + sc->memcg_low_skipped = 1; > continue; > - case MEMCG_PROT_LOW: > - /* > - * Soft protection. > - * Respect the protection only as long as > - * there is an unprotected supply > - * of reclaimable memory from other cgroups. > - */ > - if (!sc->memcg_low_reclaim) { > - sc->memcg_low_skipped = 1; > - continue; > - } > - memcg_memory_event(memcg, MEMCG_LOW); > - break; > - case MEMCG_PROT_NONE: > - /* > - * All protection thresholds breached. We may > - * still choose to vary the scan pressure > - * applied based on by how much the cgroup in > - * question has exceeded its protection > - * thresholds (see get_scan_count). > - */ > - break; > } > - > - reclaimed = sc->nr_reclaimed; > - scanned = sc->nr_scanned; > - shrink_node_memcg(pgdat, memcg, sc); > - > - if (sc->may_shrinkslab) { > - shrink_slab(sc->gfp_mask, pgdat->node_id, > - memcg, sc->priority); > - } > - > - /* Record the group's reclaim efficiency */ > - vmpressure(sc->gfp_mask, memcg, false, > - sc->nr_scanned - scanned, > - sc->nr_reclaimed - reclaimed); > - > + memcg_memory_event(memcg, MEMCG_LOW); > + break; > + case MEMCG_PROT_NONE: > /* > - * Kswapd have to scan all memory cgroups to fulfill > - * the overall scan target for the node. > - * > - * Limit reclaim, on the other hand, only cares about > - * nr_to_reclaim pages to be reclaimed and it will > - * retry with decreasing priority if one round over the > - * whole hierarchy is not sufficient. > + * All protection thresholds breached. We may > + * still choose to vary the scan pressure > + * applied based on by how much the cgroup in > + * question has exceeded its protection > + * thresholds (see get_scan_count). > */ > - if (!current_is_kswapd() && > - sc->nr_reclaimed >= sc->nr_to_reclaim) { > - mem_cgroup_iter_break(root, memcg); > - break; > - } > - } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); > + break; > + } > + > + reclaimed = sc->nr_reclaimed; > + scanned = sc->nr_scanned; > + shrink_node_memcg(pgdat, memcg, sc); > > - if (reclaim_state) { > - sc->nr_reclaimed += reclaim_state->reclaimed_slab; > - reclaim_state->reclaimed_slab = 0; > + if (sc->may_shrinkslab) { > + shrink_slab(sc->gfp_mask, pgdat->node_id, > + memcg, sc->priority); > } > > - /* Record the subtree's reclaim efficiency */ > - vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, > - sc->nr_scanned - nr_scanned, > - sc->nr_reclaimed - nr_reclaimed); > + /* Record the group's reclaim efficiency */ > + vmpressure(sc->gfp_mask, memcg, false, > + sc->nr_scanned - scanned, > + sc->nr_reclaimed - reclaimed); > > - if (sc->nr_reclaimed - nr_reclaimed) > - reclaimable = true; > + /* > + * Kswapd have to scan all memory cgroups to fulfill > + * the overall scan target for the node. > + * > + * Limit reclaim, on the other hand, only cares about > + * nr_to_reclaim pages to be reclaimed and it will > + * retry with decreasing priority if one round over the > + * whole hierarchy is not sufficient. > + */ > + if (!current_is_kswapd() && > + sc->nr_reclaimed >= sc->nr_to_reclaim) { > + mem_cgroup_iter_break(root, memcg); > + break; > + } > + } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); > > - if (current_is_kswapd()) { > - /* > - * If reclaim is isolating dirty pages under writeback, > - * it implies that the long-lived page allocation rate > - * is exceeding the page laundering rate. Either the > - * global limits are not being effective at throttling > - * processes due to the page distribution throughout > - * zones or there is heavy usage of a slow backing > - * device. The only option is to throttle from reclaim > - * context which is not ideal as there is no guarantee > - * the dirtying process is throttled in the same way > - * balance_dirty_pages() manages. > - * > - * Once a node is flagged PGDAT_WRITEBACK, kswapd will > - * count the number of pages under pages flagged for > - * immediate reclaim and stall if any are encountered > - * in the nr_immediate check below. > - */ > - if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) > - set_bit(PGDAT_WRITEBACK, &pgdat->flags); > + if (reclaim_state) { > + sc->nr_reclaimed += reclaim_state->reclaimed_slab; > + reclaim_state->reclaimed_slab = 0; > + } > > - /* > - * Tag a node as congested if all the dirty pages > - * scanned were backed by a congested BDI and > - * wait_iff_congested will stall. > - */ > - if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > - set_bit(PGDAT_CONGESTED, &pgdat->flags); > + /* Record the subtree's reclaim efficiency */ > + vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, > + sc->nr_scanned - nr_scanned, > + sc->nr_reclaimed - nr_reclaimed); > > - /* Allow kswapd to start writing pages during reclaim.*/ > - if (sc->nr.unqueued_dirty == sc->nr.file_taken) > - set_bit(PGDAT_DIRTY, &pgdat->flags); > + if (sc->nr_reclaimed - nr_reclaimed) > + reclaimable = true; > > - /* > - * If kswapd scans pages marked marked for immediate > - * reclaim and under writeback (nr_immediate), it > - * implies that pages are cycling through the LRU > - * faster than they are written so also forcibly stall. > - */ > - if (sc->nr.immediate) > - congestion_wait(BLK_RW_ASYNC, HZ/10); > - } > + if (current_is_kswapd()) { > + /* > + * If reclaim is isolating dirty pages under writeback, > + * it implies that the long-lived page allocation rate > + * is exceeding the page laundering rate. Either the > + * global limits are not being effective at throttling > + * processes due to the page distribution throughout > + * zones or there is heavy usage of a slow backing > + * device. The only option is to throttle from reclaim > + * context which is not ideal as there is no guarantee > + * the dirtying process is throttled in the same way > + * balance_dirty_pages() manages. > + * > + * Once a node is flagged PGDAT_WRITEBACK, kswapd will > + * count the number of pages under pages flagged for > + * immediate reclaim and stall if any are encountered > + * in the nr_immediate check below. > + */ > + if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) > + set_bit(PGDAT_WRITEBACK, &pgdat->flags); > > /* > - * Legacy memcg will stall in page writeback so avoid forcibly > - * stalling in wait_iff_congested(). > + * Tag a node as congested if all the dirty pages > + * scanned were backed by a congested BDI and > + * wait_iff_congested will stall. > */ > - if (cgroup_reclaim(sc) && writeback_working(sc) && > - sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > - set_memcg_congestion(pgdat, root, true); > + if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > + set_bit(PGDAT_CONGESTED, &pgdat->flags); > + > + /* Allow kswapd to start writing pages during reclaim.*/ > + if (sc->nr.unqueued_dirty == sc->nr.file_taken) > + set_bit(PGDAT_DIRTY, &pgdat->flags); > > /* > - * Stall direct reclaim for IO completions if underlying BDIs > - * and node is congested. Allow kswapd to continue until it > - * starts encountering unqueued dirty pages or cycling through > - * the LRU too quickly. > + * If kswapd scans pages marked marked for immediate > + * reclaim and under writeback (nr_immediate), it > + * implies that pages are cycling through the LRU > + * faster than they are written so also forcibly stall. > */ > - if (!sc->hibernation_mode && !current_is_kswapd() && > - current_may_throttle() && pgdat_memcg_congested(pgdat, root)) > - wait_iff_congested(BLK_RW_ASYNC, HZ/10); > + if (sc->nr.immediate) > + congestion_wait(BLK_RW_ASYNC, HZ/10); > + } > + > + /* > + * Legacy memcg will stall in page writeback so avoid forcibly > + * stalling in wait_iff_congested(). > + */ > + if (cgroup_reclaim(sc) && writeback_working(sc) && > + sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > + set_memcg_congestion(pgdat, root, true); > + > + /* > + * Stall direct reclaim for IO completions if underlying BDIs > + * and node is congested. Allow kswapd to continue until it > + * starts encountering unqueued dirty pages or cycling through > + * the LRU too quickly. > + */ > + if (!sc->hibernation_mode && !current_is_kswapd() && > + current_may_throttle() && pgdat_memcg_congested(pgdat, root)) > + wait_iff_congested(BLK_RW_ASYNC, HZ/10); > > - } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, > - sc->nr_scanned - nr_scanned, sc)); > + if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, > + sc->nr_scanned - nr_scanned, sc)) > + goto again; > > /* > * Kswapd gives up on balancing particular nodes after too > -- > 2.21.0 >
diff --git a/mm/vmscan.c b/mm/vmscan.c index afd5e2432a8e..304974481146 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2672,164 +2672,164 @@ static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) { struct reclaim_state *reclaim_state = current->reclaim_state; + struct mem_cgroup *root = sc->target_mem_cgroup; + struct mem_cgroup_reclaim_cookie reclaim = { + .pgdat = pgdat, + .priority = sc->priority, + }; unsigned long nr_reclaimed, nr_scanned; bool reclaimable = false; + struct mem_cgroup *memcg; - do { - struct mem_cgroup *root = sc->target_mem_cgroup; - struct mem_cgroup_reclaim_cookie reclaim = { - .pgdat = pgdat, - .priority = sc->priority, - }; - struct mem_cgroup *memcg; - - memset(&sc->nr, 0, sizeof(sc->nr)); +again: + memset(&sc->nr, 0, sizeof(sc->nr)); - nr_reclaimed = sc->nr_reclaimed; - nr_scanned = sc->nr_scanned; + nr_reclaimed = sc->nr_reclaimed; + nr_scanned = sc->nr_scanned; - memcg = mem_cgroup_iter(root, NULL, &reclaim); - do { - unsigned long reclaimed; - unsigned long scanned; + memcg = mem_cgroup_iter(root, NULL, &reclaim); + do { + unsigned long reclaimed; + unsigned long scanned; - switch (mem_cgroup_protected(root, memcg)) { - case MEMCG_PROT_MIN: - /* - * Hard protection. - * If there is no reclaimable memory, OOM. - */ + switch (mem_cgroup_protected(root, memcg)) { + case MEMCG_PROT_MIN: + /* + * Hard protection. + * If there is no reclaimable memory, OOM. + */ + continue; + case MEMCG_PROT_LOW: + /* + * Soft protection. + * Respect the protection only as long as + * there is an unprotected supply + * of reclaimable memory from other cgroups. + */ + if (!sc->memcg_low_reclaim) { + sc->memcg_low_skipped = 1; continue; - case MEMCG_PROT_LOW: - /* - * Soft protection. - * Respect the protection only as long as - * there is an unprotected supply - * of reclaimable memory from other cgroups. - */ - if (!sc->memcg_low_reclaim) { - sc->memcg_low_skipped = 1; - continue; - } - memcg_memory_event(memcg, MEMCG_LOW); - break; - case MEMCG_PROT_NONE: - /* - * All protection thresholds breached. We may - * still choose to vary the scan pressure - * applied based on by how much the cgroup in - * question has exceeded its protection - * thresholds (see get_scan_count). - */ - break; } - - reclaimed = sc->nr_reclaimed; - scanned = sc->nr_scanned; - shrink_node_memcg(pgdat, memcg, sc); - - if (sc->may_shrinkslab) { - shrink_slab(sc->gfp_mask, pgdat->node_id, - memcg, sc->priority); - } - - /* Record the group's reclaim efficiency */ - vmpressure(sc->gfp_mask, memcg, false, - sc->nr_scanned - scanned, - sc->nr_reclaimed - reclaimed); - + memcg_memory_event(memcg, MEMCG_LOW); + break; + case MEMCG_PROT_NONE: /* - * Kswapd have to scan all memory cgroups to fulfill - * the overall scan target for the node. - * - * Limit reclaim, on the other hand, only cares about - * nr_to_reclaim pages to be reclaimed and it will - * retry with decreasing priority if one round over the - * whole hierarchy is not sufficient. + * All protection thresholds breached. We may + * still choose to vary the scan pressure + * applied based on by how much the cgroup in + * question has exceeded its protection + * thresholds (see get_scan_count). */ - if (!current_is_kswapd() && - sc->nr_reclaimed >= sc->nr_to_reclaim) { - mem_cgroup_iter_break(root, memcg); - break; - } - } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); + break; + } + + reclaimed = sc->nr_reclaimed; + scanned = sc->nr_scanned; + shrink_node_memcg(pgdat, memcg, sc); - if (reclaim_state) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; + if (sc->may_shrinkslab) { + shrink_slab(sc->gfp_mask, pgdat->node_id, + memcg, sc->priority); } - /* Record the subtree's reclaim efficiency */ - vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, - sc->nr_scanned - nr_scanned, - sc->nr_reclaimed - nr_reclaimed); + /* Record the group's reclaim efficiency */ + vmpressure(sc->gfp_mask, memcg, false, + sc->nr_scanned - scanned, + sc->nr_reclaimed - reclaimed); - if (sc->nr_reclaimed - nr_reclaimed) - reclaimable = true; + /* + * Kswapd have to scan all memory cgroups to fulfill + * the overall scan target for the node. + * + * Limit reclaim, on the other hand, only cares about + * nr_to_reclaim pages to be reclaimed and it will + * retry with decreasing priority if one round over the + * whole hierarchy is not sufficient. + */ + if (!current_is_kswapd() && + sc->nr_reclaimed >= sc->nr_to_reclaim) { + mem_cgroup_iter_break(root, memcg); + break; + } + } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); - if (current_is_kswapd()) { - /* - * If reclaim is isolating dirty pages under writeback, - * it implies that the long-lived page allocation rate - * is exceeding the page laundering rate. Either the - * global limits are not being effective at throttling - * processes due to the page distribution throughout - * zones or there is heavy usage of a slow backing - * device. The only option is to throttle from reclaim - * context which is not ideal as there is no guarantee - * the dirtying process is throttled in the same way - * balance_dirty_pages() manages. - * - * Once a node is flagged PGDAT_WRITEBACK, kswapd will - * count the number of pages under pages flagged for - * immediate reclaim and stall if any are encountered - * in the nr_immediate check below. - */ - if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) - set_bit(PGDAT_WRITEBACK, &pgdat->flags); + if (reclaim_state) { + sc->nr_reclaimed += reclaim_state->reclaimed_slab; + reclaim_state->reclaimed_slab = 0; + } - /* - * Tag a node as congested if all the dirty pages - * scanned were backed by a congested BDI and - * wait_iff_congested will stall. - */ - if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) - set_bit(PGDAT_CONGESTED, &pgdat->flags); + /* Record the subtree's reclaim efficiency */ + vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, + sc->nr_scanned - nr_scanned, + sc->nr_reclaimed - nr_reclaimed); - /* Allow kswapd to start writing pages during reclaim.*/ - if (sc->nr.unqueued_dirty == sc->nr.file_taken) - set_bit(PGDAT_DIRTY, &pgdat->flags); + if (sc->nr_reclaimed - nr_reclaimed) + reclaimable = true; - /* - * If kswapd scans pages marked marked for immediate - * reclaim and under writeback (nr_immediate), it - * implies that pages are cycling through the LRU - * faster than they are written so also forcibly stall. - */ - if (sc->nr.immediate) - congestion_wait(BLK_RW_ASYNC, HZ/10); - } + if (current_is_kswapd()) { + /* + * If reclaim is isolating dirty pages under writeback, + * it implies that the long-lived page allocation rate + * is exceeding the page laundering rate. Either the + * global limits are not being effective at throttling + * processes due to the page distribution throughout + * zones or there is heavy usage of a slow backing + * device. The only option is to throttle from reclaim + * context which is not ideal as there is no guarantee + * the dirtying process is throttled in the same way + * balance_dirty_pages() manages. + * + * Once a node is flagged PGDAT_WRITEBACK, kswapd will + * count the number of pages under pages flagged for + * immediate reclaim and stall if any are encountered + * in the nr_immediate check below. + */ + if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) + set_bit(PGDAT_WRITEBACK, &pgdat->flags); /* - * Legacy memcg will stall in page writeback so avoid forcibly - * stalling in wait_iff_congested(). + * Tag a node as congested if all the dirty pages + * scanned were backed by a congested BDI and + * wait_iff_congested will stall. */ - if (cgroup_reclaim(sc) && writeback_working(sc) && - sc->nr.dirty && sc->nr.dirty == sc->nr.congested) - set_memcg_congestion(pgdat, root, true); + if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) + set_bit(PGDAT_CONGESTED, &pgdat->flags); + + /* Allow kswapd to start writing pages during reclaim.*/ + if (sc->nr.unqueued_dirty == sc->nr.file_taken) + set_bit(PGDAT_DIRTY, &pgdat->flags); /* - * Stall direct reclaim for IO completions if underlying BDIs - * and node is congested. Allow kswapd to continue until it - * starts encountering unqueued dirty pages or cycling through - * the LRU too quickly. + * If kswapd scans pages marked marked for immediate + * reclaim and under writeback (nr_immediate), it + * implies that pages are cycling through the LRU + * faster than they are written so also forcibly stall. */ - if (!sc->hibernation_mode && !current_is_kswapd() && - current_may_throttle() && pgdat_memcg_congested(pgdat, root)) - wait_iff_congested(BLK_RW_ASYNC, HZ/10); + if (sc->nr.immediate) + congestion_wait(BLK_RW_ASYNC, HZ/10); + } + + /* + * Legacy memcg will stall in page writeback so avoid forcibly + * stalling in wait_iff_congested(). + */ + if (cgroup_reclaim(sc) && writeback_working(sc) && + sc->nr.dirty && sc->nr.dirty == sc->nr.congested) + set_memcg_congestion(pgdat, root, true); + + /* + * Stall direct reclaim for IO completions if underlying BDIs + * and node is congested. Allow kswapd to continue until it + * starts encountering unqueued dirty pages or cycling through + * the LRU too quickly. + */ + if (!sc->hibernation_mode && !current_is_kswapd() && + current_may_throttle() && pgdat_memcg_congested(pgdat, root)) + wait_iff_congested(BLK_RW_ASYNC, HZ/10); - } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, - sc->nr_scanned - nr_scanned, sc)); + if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, + sc->nr_scanned - nr_scanned, sc)) + goto again; /* * Kswapd gives up on balancing particular nodes after too
Most of the function body is inside a loop, which imposes an additional indentation and scoping level that makes the code a bit hard to follow and modify. The looping only happens in case of reclaim-compaction, which isn't the common case. So rather than adding yet another function level to the reclaim path and have every reclaim invocation go through a level that only exists for one specific cornercase, use a retry goto. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- mm/vmscan.c | 266 ++++++++++++++++++++++++++-------------------------- 1 file changed, 133 insertions(+), 133 deletions(-)