On Tue, Jun 18, 2024 at 11:14:33PM +0530, Anand Khoje wrote: > > On 6/16/24 21:14, Leon Romanovsky wrote: > > On Fri, Jun 14, 2024 at 01:31:35PM +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@xxxxxxxxxx> > > > --- > > > Changes in v3: > > > - Shifted the logic to function req_pages_handler() as per > > > Leon's suggestion. > > > --- > > > drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c | 7 ++++++- > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > > The title has extra space: > > "net/mlx5 : Reclaim max 50K pages at once" -> "net/mlx5: Reclaim max 50K pages at once" > > > > But the code looks good to me. > > > > Thanks, > > Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx> > > Hi Leon, > > Thanks for providing the R-B. Should I send a v4 with the fix for the extra > space issue? Yes, please. And run get_maintainer.pl to get the correct email address for the maintainers and ML. This patch will be applied by netdev maintainers. Thanks > > -Anand >
