From: Minchan Kim <[email protected]>
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 <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
---
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
On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote:
> From: Minchan Kim <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Minchan Kim <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
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.
*/
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 <[email protected]>
> >
> > 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 <[email protected]>
> > Signed-off-by: Minchan Kim <[email protected]>
>
> Acked-by: Johannes Weiner <[email protected]>
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 <[email protected]>
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 <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
---
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
On Thu, Oct 10, 2019 at 3:11 PM Minchan Kim <[email protected]> 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 <[email protected]>
> > >
> > > 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 <[email protected]>
> > > Signed-off-by: Minchan Kim <[email protected]>
> >
> > Acked-by: Johannes Weiner <[email protected]>
>
> 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 <[email protected]>
> 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 <[email protected]>
> Signed-off-by: Minchan Kim <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
> ---
> 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
>
On Thu, 10 Oct 2019 15:17:47 -0400 Johannes Weiner <[email protected]> wrote:
> On Thu, Oct 10, 2019 at 08:21:34AM -0700, Minchan Kim wrote:
> > From: Minchan Kim <[email protected]>
> >
> > 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 <[email protected]>
> > Signed-off-by: Minchan Kim <[email protected]>
>
> Acked-by: Johannes Weiner <[email protected]>
>
> 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) {
_