* [PATCH] mm: annotate refault stalls from swap_readpage @ 2019-10-10 15:21 Minchan Kim 2019-10-10 19:17 ` Johannes Weiner 0 siblings, 1 reply; 5+ messages in thread From: Minchan Kim @ 2019-10-10 15:21 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-mm, LKML, Sahkeel Butt, Minchan Kim, Johannes Weiner From: Minchan Kim <minchan@google.com> If block device supports rw_page operation, it doesn't submit bio so annotation in submit_bio for refault stall doesn't work. It happens with zram in android, especially swap read path which could consume CPU cycle for decompress. It is also a problem for zswap which uses frontswap. Annotate swap_readpage() to account the synchronous IO overhead to prevent underreport memory pressure. Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Minchan Kim <minchan@google.com> --- mm/page_io.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/page_io.c b/mm/page_io.c index 24ee600f9131..20147473d4a5 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -22,6 +22,7 @@ #include <linux/writeback.h> #include <linux/frontswap.h> #include <linux/blkdev.h> +#include <linux/psi.h> #include <linux/uio.h> #include <linux/sched/task.h> #include <asm/pgtable.h> @@ -354,10 +355,14 @@ int swap_readpage(struct page *page, bool synchronous) struct swap_info_struct *sis = page_swap_info(page); blk_qc_t qc; struct gendisk *disk; + unsigned long pflags; VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageUptodate(page), page); + + psi_memstall_enter(&pflags); + if (frontswap_load(page) == 0) { SetPageUptodate(page); unlock_page(page); @@ -371,7 +376,7 @@ int swap_readpage(struct page *page, bool synchronous) ret = mapping->a_ops->readpage(swap_file, page); if (!ret) count_vm_event(PSWPIN); - return ret; + goto out; } ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); @@ -382,7 +387,7 @@ int swap_readpage(struct page *page, bool synchronous) } count_vm_event(PSWPIN); - return 0; + goto out; } ret = 0; @@ -418,6 +423,7 @@ int swap_readpage(struct page *page, bool synchronous) bio_put(bio); out: + psi_memstall_leave(&pflags); return ret; } -- 2.23.0.581.g78d2f28ef7-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: annotate refault stalls from swap_readpage 2019-10-10 15:21 [PATCH] mm: annotate refault stalls from swap_readpage Minchan Kim @ 2019-10-10 19:17 ` Johannes Weiner 2019-10-10 22:11 ` Minchan Kim 2019-10-11 21:32 ` Andrew Morton 0 siblings, 2 replies; 5+ messages in thread From: Johannes Weiner @ 2019-10-10 19:17 UTC (permalink / raw) To: Minchan Kim; +Cc: Andrew Morton, linux-mm, LKML, Sahkeel Butt, Minchan Kim On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote: > From: Minchan Kim <minchan@google.com> > > If block device supports rw_page operation, it doesn't submit bio > so annotation in submit_bio for refault stall doesn't work. > It happens with zram in android, especially swap read path which > could consume CPU cycle for decompress. It is also a problem for > zswap which uses frontswap. > > Annotate swap_readpage() to account the synchronous IO overhead > to prevent underreport memory pressure. > > Cc: Johannes Weiner <hannes@cmpxchg.org> > Signed-off-by: Minchan Kim <minchan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Can you please add a comment to the caller? Lifted from submit_bio(): /* * Count submission time as memory stall. When the device is * congested, or the submitting cgroup IO-throttled, * submission can be a significant part of overall IO time. */ ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: annotate refault stalls from swap_readpage 2019-10-10 19:17 ` Johannes Weiner @ 2019-10-10 22:11 ` Minchan Kim 2019-10-11 17:32 ` Shakeel Butt 2019-10-11 21:32 ` Andrew Morton 1 sibling, 1 reply; 5+ messages in thread From: Minchan Kim @ 2019-10-10 22:11 UTC (permalink / raw) To: Johannes Weiner; +Cc: Andrew Morton, linux-mm, LKML, Sahkeel Butt On Thu, Oct 10, 2019 at 03:17:47PM -0400, Johannes Weiner wrote: > On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote: > > From: Minchan Kim <minchan@google.com> > > > > If block device supports rw_page operation, it doesn't submit bio > > so annotation in submit_bio for refault stall doesn't work. > > It happens with zram in android, especially swap read path which > > could consume CPU cycle for decompress. It is also a problem for > > zswap which uses frontswap. > > > > Annotate swap_readpage() to account the synchronous IO overhead > > to prevent underreport memory pressure. > > > > Cc: Johannes Weiner <hannes@cmpxchg.org> > > Signed-off-by: Minchan Kim <minchan@google.com> > > Acked-by: Johannes Weiner <hannes@cmpxchg.org> Thanks, Johannes! > > Can you please add a comment to the caller? Lifted from submit_bio(): Sure, I added a little about zram. > > /* > * Count submission time as memory stall. When the device is > * congested, or the submitting cgroup IO-throttled, > * submission can be a significant part of overall IO time. > */ From a8ae7cbc2d3f050aca810fd68285d45cb933b825 Mon Sep 17 00:00:00 2001 From: Minchan Kim <minchan@google.com> Date: Thu, 10 Oct 2019 08:09:06 -0700 Subject: [PATCH v2] mm: annotate refault stalls from swap_readpage If block device supports rw_page operation, it doesn't submit bio so annotation in submit_bio for refault stall doesn't work. It happens with zram in android, especially swap read path which could consume CPU cycle for decompress. It is also a problem for zswap which uses frontswap. Annotate swap_readpage() to account the synchronous IO overhead to prevent underreport memory pressure. Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Minchan Kim <minchan@google.com> --- mm/page_io.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/mm/page_io.c b/mm/page_io.c index 24ee600f9131..18f1f8e1d27f 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -22,6 +22,7 @@ #include <linux/writeback.h> #include <linux/frontswap.h> #include <linux/blkdev.h> +#include <linux/psi.h> #include <linux/uio.h> #include <linux/sched/task.h> #include <asm/pgtable.h> @@ -354,10 +355,20 @@ int swap_readpage(struct page *page, bool synchronous) struct swap_info_struct *sis = page_swap_info(page); blk_qc_t qc; struct gendisk *disk; + unsigned long pflags; VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageUptodate(page), page); + + /* + * Count submission time as memory stall. When the device is + * congested, the submitting cgroup IO-throttled, or backing + * device works synchronously(e.g., zram), submission can be + * a significant part of overall IO time. + */ + psi_memstall_enter(&pflags); + if (frontswap_load(page) == 0) { SetPageUptodate(page); unlock_page(page); @@ -371,7 +382,7 @@ int swap_readpage(struct page *page, bool synchronous) ret = mapping->a_ops->readpage(swap_file, page); if (!ret) count_vm_event(PSWPIN); - return ret; + goto out; } ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); @@ -382,7 +393,7 @@ int swap_readpage(struct page *page, bool synchronous) } count_vm_event(PSWPIN); - return 0; + goto out; } ret = 0; @@ -418,6 +429,7 @@ int swap_readpage(struct page *page, bool synchronous) bio_put(bio); out: + psi_memstall_leave(&pflags); return ret; } -- 2.23.0.581.g78d2f28ef7-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: annotate refault stalls from swap_readpage 2019-10-10 22:11 ` Minchan Kim @ 2019-10-11 17:32 ` Shakeel Butt 0 siblings, 0 replies; 5+ messages in thread From: Shakeel Butt @ 2019-10-11 17:32 UTC (permalink / raw) To: Minchan Kim; +Cc: Johannes Weiner, Andrew Morton, linux-mm, LKML On Thu, Oct 10, 2019 at 3:11 PM Minchan Kim <minchan@kernel.org> wrote: > > On Thu, Oct 10, 2019 at 03:17:47PM -0400, Johannes Weiner wrote: > > On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote: > > > From: Minchan Kim <minchan@google.com> > > > > > > If block device supports rw_page operation, it doesn't submit bio > > > so annotation in submit_bio for refault stall doesn't work. > > > It happens with zram in android, especially swap read path which > > > could consume CPU cycle for decompress. It is also a problem for > > > zswap which uses frontswap. > > > > > > Annotate swap_readpage() to account the synchronous IO overhead > > > to prevent underreport memory pressure. > > > > > > Cc: Johannes Weiner <hannes@cmpxchg.org> > > > Signed-off-by: Minchan Kim <minchan@google.com> > > > > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > > Thanks, Johannes! > > > > > Can you please add a comment to the caller? Lifted from submit_bio(): > > Sure, I added a little about zram. > > > > > /* > > * Count submission time as memory stall. When the device is > > * congested, or the submitting cgroup IO-throttled, > > * submission can be a significant part of overall IO time. > > */ > > > From a8ae7cbc2d3f050aca810fd68285d45cb933b825 Mon Sep 17 00:00:00 2001 > From: Minchan Kim <minchan@google.com> > Date: Thu, 10 Oct 2019 08:09:06 -0700 > Subject: [PATCH v2] mm: annotate refault stalls from swap_readpage > > If block device supports rw_page operation, it doesn't submit bio > so annotation in submit_bio for refault stall doesn't work. > It happens with zram in android, especially swap read path which > could consume CPU cycle for decompress. It is also a problem for > zswap which uses frontswap. > > Annotate swap_readpage() to account the synchronous IO overhead > to prevent underreport memory pressure. > > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > Signed-off-by: Minchan Kim <minchan@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> > --- > mm/page_io.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/mm/page_io.c b/mm/page_io.c > index 24ee600f9131..18f1f8e1d27f 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -22,6 +22,7 @@ > #include <linux/writeback.h> > #include <linux/frontswap.h> > #include <linux/blkdev.h> > +#include <linux/psi.h> > #include <linux/uio.h> > #include <linux/sched/task.h> > #include <asm/pgtable.h> > @@ -354,10 +355,20 @@ int swap_readpage(struct page *page, bool synchronous) > struct swap_info_struct *sis = page_swap_info(page); > blk_qc_t qc; > struct gendisk *disk; > + unsigned long pflags; > > VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page); > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(PageUptodate(page), page); > + > + /* > + * Count submission time as memory stall. When the device is > + * congested, the submitting cgroup IO-throttled, or backing > + * device works synchronously(e.g., zram), submission can be > + * a significant part of overall IO time. > + */ > + psi_memstall_enter(&pflags); > + > if (frontswap_load(page) == 0) { > SetPageUptodate(page); > unlock_page(page); > @@ -371,7 +382,7 @@ int swap_readpage(struct page *page, bool synchronous) > ret = mapping->a_ops->readpage(swap_file, page); > if (!ret) > count_vm_event(PSWPIN); > - return ret; > + goto out; > } > > ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); > @@ -382,7 +393,7 @@ int swap_readpage(struct page *page, bool synchronous) > } > > count_vm_event(PSWPIN); > - return 0; > + goto out; > } > > ret = 0; > @@ -418,6 +429,7 @@ int swap_readpage(struct page *page, bool synchronous) > bio_put(bio); > > out: > + psi_memstall_leave(&pflags); > return ret; > } > > -- > 2.23.0.581.g78d2f28ef7-goog > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: annotate refault stalls from swap_readpage 2019-10-10 19:17 ` Johannes Weiner 2019-10-10 22:11 ` Minchan Kim @ 2019-10-11 21:32 ` Andrew Morton 1 sibling, 0 replies; 5+ messages in thread From: Andrew Morton @ 2019-10-11 21:32 UTC (permalink / raw) To: Johannes Weiner; +Cc: Minchan Kim, linux-mm, LKML, Sahkeel Butt, Minchan Kim On Thu, 10 Oct 2019 15:17:47 -0400 Johannes Weiner <hannes@cmpxchg.org> wrote: > On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote: > > From: Minchan Kim <minchan@google.com> > > > > If block device supports rw_page operation, it doesn't submit bio > > so annotation in submit_bio for refault stall doesn't work. > > It happens with zram in android, especially swap read path which > > could consume CPU cycle for decompress. It is also a problem for > > zswap which uses frontswap. > > > > Annotate swap_readpage() to account the synchronous IO overhead > > to prevent underreport memory pressure. > > > > Cc: Johannes Weiner <hannes@cmpxchg.org> > > Signed-off-by: Minchan Kim <minchan@google.com> > > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > > Can you please add a comment to the caller? Lifted from submit_bio(): > > /* > * Count submission time as memory stall. When the device is > * congested, or the submitting cgroup IO-throttled, > * submission can be a significant part of overall IO time. > */ This? --- a/mm/page_io.c~mm-annotate-refault-stalls-from-swap_readpage-fix +++ a/mm/page_io.c @@ -361,6 +361,11 @@ int swap_readpage(struct page *page, boo VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageUptodate(page), page); + /* + * Count submission time as memory stall. When the device is congested, + * or the submitting cgroup IO-throttled, submission can be a + * significant part of overall IO time. + */ psi_memstall_enter(&pflags); if (frontswap_load(page) == 0) { _ ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-10-11 21:32 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-10-10 15:21 [PATCH] mm: annotate refault stalls from swap_readpage Minchan Kim 2019-10-10 19:17 ` Johannes Weiner 2019-10-10 22:11 ` Minchan Kim 2019-10-11 17:32 ` Shakeel Butt 2019-10-11 21:32 ` Andrew Morton
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