| Message ID | 20240613121252.93315-1-anand.a.khoje@oracle.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v2] RDMA/mlx5 : Reclaim max 50K pages at once | expand |
On Thu, Jun 13, 2024 at 05:42:52PM +0530, Anand Khoje wrote: > In non FLR context, at times CX-5 requests release of ~8 million FW pages. > This needs humongous number of cmd mailboxes, which to be released once > the pages are reclaimed. Release of humongous number of cmd mailboxes is > consuming cpu time running into many seconds. Which with non preemptible > kernels is leading to critical process starving on that cpu’s RQ. > To alleviate this, this change restricts the total number of pages > a worker will try to reclaim maximum 50K pages in one go. > The limit 50K is aligned with the current firmware capacity/limit of > releasing 50K pages at once per MLX5_CMD_OP_MANAGE_PAGES + MLX5_PAGES_TAKE > device command. > > Our tests have shown significant benefit of this change in terms of > time consumed by dma_pool_free(). > During a test where an event was raised by HCA > to release 1.3 Million pages, following observations were made: > > - Without this change: > Number of mailbox messages allocated was around 20K, to accommodate > the DMA addresses of 1.3 million pages. > The average time spent by dma_pool_free() to free the DMA pool is between > 16 usec to 32 usec. > value ------------- Distribution ------------- count > 256 | 0 > 512 |@ 287 > 1024 |@@@ 1332 > 2048 |@ 656 > 4096 |@@@@@ 2599 > 8192 |@@@@@@@@@@ 4755 > 16384 |@@@@@@@@@@@@@@@ 7545 > 32768 |@@@@@ 2501 > 65536 | 0 > > - With this change: > Number of mailbox messages allocated was around 800; this was to > accommodate DMA addresses of only 50K pages. > The average time spent by dma_pool_free() to free the DMA pool in this case > lies between 1 usec to 2 usec. > value ------------- Distribution ------------- count > 256 | 0 > 512 |@@@@@@@@@@@@@@@@@@ 346 > 1024 |@@@@@@@@@@@@@@@@@@@@@@ 435 > 2048 | 0 > 4096 | 0 > 8192 | 1 > 16384 | 0 > > Signed-off-by: Anand Khoje <anand.a.khoje@oracle.com> > --- > Changes in v2: > - In v1, CPUs were yielded if more than 2 msec are spent in > mlx5_free_cmd_msg(). The approach to limit the time spent is changed > in this version. > --- > drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c > index 1b38397..b1cf97d 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c > @@ -482,12 +482,16 @@ static int reclaim_pages(struct mlx5_core_dev *dev, u32 func_id, int npages, > return err; > } > > +#define MAX_RECLAIM_NPAGES -50000 > static void pages_work_handler(struct work_struct *work) > { > struct mlx5_pages_req *req = container_of(work, struct mlx5_pages_req, work); > struct mlx5_core_dev *dev = req->dev; > int err = 0; > > + if (req->npages < MAX_RECLAIM_NPAGES) > + req->npages = MAX_RECLAIM_NPAGES; I like this change more than previous variant with yield. Regarding the patch: 1. Please limit the number of pages in req_pages_handler() and not int pages_work_handler(). 2. Patch title should be "net/mlx5: Reclaim max 50K pages at once" and not "RDMA...". 3. You should run get_maintainer.pl script to find the right maintainers and add them to the TO or CC list. And I still think that you will get better performance by parallelizing the reclaim process. Thanks > + > if (req->release_all) > release_all_pages(dev, req->func_id, req->ec_function); > else if (req->npages < 0) > -- > 1.8.3.1 > >
On 6/14/24 00:33, Leon Romanovsky wrote: > On Thu, Jun 13, 2024 at 05:42:52PM +0530, Anand Khoje wrote: >> In non FLR context, at times CX-5 requests release of ~8 million FW pages. >> This needs humongous number of cmd mailboxes, which to be released once >> the pages are reclaimed. Release of humongous number of cmd mailboxes is >> consuming cpu time running into many seconds. Which with non preemptible >> kernels is leading to critical process starving on that cpu’s RQ. >> To alleviate this, this change restricts the total number of pages >> a worker will try to reclaim maximum 50K pages in one go. >> The limit 50K is aligned with the current firmware capacity/limit of >> releasing 50K pages at once per MLX5_CMD_OP_MANAGE_PAGES + MLX5_PAGES_TAKE >> device command. >> >> Our tests have shown significant benefit of this change in terms of >> time consumed by dma_pool_free(). >> During a test where an event was raised by HCA >> to release 1.3 Million pages, following observations were made: >> >> - Without this change: >> Number of mailbox messages allocated was around 20K, to accommodate >> the DMA addresses of 1.3 million pages. >> The average time spent by dma_pool_free() to free the DMA pool is between >> 16 usec to 32 usec. >> value ------------- Distribution ------------- count >> 256 | 0 >> 512 |@ 287 >> 1024 |@@@ 1332 >> 2048 |@ 656 >> 4096 |@@@@@ 2599 >> 8192 |@@@@@@@@@@ 4755 >> 16384 |@@@@@@@@@@@@@@@ 7545 >> 32768 |@@@@@ 2501 >> 65536 | 0 >> >> - With this change: >> Number of mailbox messages allocated was around 800; this was to >> accommodate DMA addresses of only 50K pages. >> The average time spent by dma_pool_free() to free the DMA pool in this case >> lies between 1 usec to 2 usec. >> value ------------- Distribution ------------- count >> 256 | 0 >> 512 |@@@@@@@@@@@@@@@@@@ 346 >> 1024 |@@@@@@@@@@@@@@@@@@@@@@ 435 >> 2048 | 0 >> 4096 | 0 >> 8192 | 1 >> 16384 | 0 >> >> Signed-off-by: Anand Khoje <anand.a.khoje@oracle.com> >> --- >> Changes in v2: >> - In v1, CPUs were yielded if more than 2 msec are spent in >> mlx5_free_cmd_msg(). The approach to limit the time spent is changed >> in this version. >> --- >> drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c >> index 1b38397..b1cf97d 100644 >> --- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c >> +++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c >> @@ -482,12 +482,16 @@ static int reclaim_pages(struct mlx5_core_dev *dev, u32 func_id, int npages, >> return err; >> } >> >> +#define MAX_RECLAIM_NPAGES -50000 >> static void pages_work_handler(struct work_struct *work) >> { >> struct mlx5_pages_req *req = container_of(work, struct mlx5_pages_req, work); >> struct mlx5_core_dev *dev = req->dev; >> int err = 0; >> >> + if (req->npages < MAX_RECLAIM_NPAGES) >> + req->npages = MAX_RECLAIM_NPAGES; > I like this change more than previous variant with yield. > Regarding the patch: > 1. Please limit the number of pages in req_pages_handler() and not int pages_work_handler(). > 2. Patch title should be "net/mlx5: Reclaim max 50K pages at once" and not "RDMA...". > 3. You should run get_maintainer.pl script to find the right maintainers and add them to the TO or CC list. > > And I still think that you will get better performance by parallelizing the reclaim process. > > Thanks Hi Leon, Thanks for the comments. I will make the changes and resend a v3. -Anand >> + >> if (req->release_all) >> release_all_pages(dev, req->func_id, req->ec_function); >> else if (req->npages < 0) >> -- >> 1.8.3.1 >> >>
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c index 1b38397..b1cf97d 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c @@ -482,12 +482,16 @@ static int reclaim_pages(struct mlx5_core_dev *dev, u32 func_id, int npages, return err; } +#define MAX_RECLAIM_NPAGES -50000 static void pages_work_handler(struct work_struct *work) { struct mlx5_pages_req *req = container_of(work, struct mlx5_pages_req, work); struct mlx5_core_dev *dev = req->dev; int err = 0; + if (req->npages < MAX_RECLAIM_NPAGES) + req->npages = MAX_RECLAIM_NPAGES; + if (req->release_all) release_all_pages(dev, req->func_id, req->ec_function); else if (req->npages < 0)
In non FLR context, at times CX-5 requests release of ~8 million FW pages. This needs humongous number of cmd mailboxes, which to be released once the pages are reclaimed. Release of humongous number of cmd mailboxes is consuming cpu time running into many seconds. Which with non preemptible kernels is leading to critical process starving on that cpu’s RQ. To alleviate this, this change restricts the total number of pages a worker will try to reclaim maximum 50K pages in one go. The limit 50K is aligned with the current firmware capacity/limit of releasing 50K pages at once per MLX5_CMD_OP_MANAGE_PAGES + MLX5_PAGES_TAKE device command. Our tests have shown significant benefit of this change in terms of time consumed by dma_pool_free(). During a test where an event was raised by HCA to release 1.3 Million pages, following observations were made: - Without this change: Number of mailbox messages allocated was around 20K, to accommodate the DMA addresses of 1.3 million pages. The average time spent by dma_pool_free() to free the DMA pool is between 16 usec to 32 usec. value ------------- Distribution ------------- count 256 | 0 512 |@ 287 1024 |@@@ 1332 2048 |@ 656 4096 |@@@@@ 2599 8192 |@@@@@@@@@@ 4755 16384 |@@@@@@@@@@@@@@@ 7545 32768 |@@@@@ 2501 65536 | 0 - With this change: Number of mailbox messages allocated was around 800; this was to accommodate DMA addresses of only 50K pages. The average time spent by dma_pool_free() to free the DMA pool in this case lies between 1 usec to 2 usec. value ------------- Distribution ------------- count 256 | 0 512 |@@@@@@@@@@@@@@@@@@ 346 1024 |@@@@@@@@@@@@@@@@@@@@@@ 435 2048 | 0 4096 | 0 8192 | 1 16384 | 0 Signed-off-by: Anand Khoje <anand.a.khoje@oracle.com> --- Changes in v2: - In v1, CPUs were yielded if more than 2 msec are spent in mlx5_free_cmd_msg(). The approach to limit the time spent is changed in this version. --- drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c | 4 ++++ 1 file changed, 4 insertions(+)