From: Mike Rapoport <rppt@linux.ibm.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Jeremy Cline <jcline@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately
Date: Wed, 19 Feb 2020 09:23:03 +0100 [thread overview]
Message-ID: <20200219082303.GA32242@linux.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2002181828400.108053@chino.kir.corp.google.com>
On Tue, Feb 18, 2020 at 06:29:21PM -0800, David Rientjes wrote:
> The thp_fault_fallback stat in /proc/vmstat is incremented if either the
> hugepage allocation fails through the page allocator or the hugepage
> charge fails through mem cgroup.
>
> This patch leaves this field untouched but adds a new field,
> thp_fault_fallback_charge, which is incremented only when the mem cgroup
> charge fails.
>
> This distinguishes between faults that want to be backed by hugepages but
> fail due to fragmentation (or low memory conditions) and those that fail
> due to mem cgroup limits. That can be used to determine the impact of
> fragmentation on the system by excluding faults that failed due to memcg
> usage.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> # Documentation
> ---
> v2:
> - supported for shmem faults as well per Kirill
> - fixed worked in documentation and commit description per Mike
>
> Documentation/admin-guide/mm/transhuge.rst | 5 +++++
> include/linux/vm_event_item.h | 1 +
> mm/huge_memory.c | 2 ++
> mm/shmem.c | 4 +++-
> mm/vmstat.c | 1 +
> 5 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
> --- a/Documentation/admin-guide/mm/transhuge.rst
> +++ b/Documentation/admin-guide/mm/transhuge.rst
> @@ -310,6 +310,11 @@ thp_fault_fallback
> is incremented if a page fault fails to allocate
> a huge page and instead falls back to using small pages.
>
> +thp_fault_fallback_charge
> + is incremented if a page fault fails to charge a huge page and
> + instead falls back to using small pages even though the
> + allocation was successful.
> +
> thp_collapse_alloc_failed
> is incremented if khugepaged found a range
> of pages that should be collapsed into one huge page but failed
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -73,6 +73,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> THP_FAULT_ALLOC,
> THP_FAULT_FALLBACK,
> + THP_FAULT_FALLBACK_CHARGE,
> THP_COLLAPSE_ALLOC,
> THP_COLLAPSE_ALLOC_FAILED,
> THP_FILE_ALLOC,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -597,6 +597,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
> if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
> put_page(page);
> count_vm_event(THP_FAULT_FALLBACK);
> + count_vm_event(THP_FAULT_FALLBACK_CHARGE);
> return VM_FAULT_FALLBACK;
> }
>
> @@ -1406,6 +1407,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
> put_page(page);
> ret |= VM_FAULT_FALLBACK;
> count_vm_event(THP_FAULT_FALLBACK);
> + count_vm_event(THP_FAULT_FALLBACK_CHARGE);
> goto out;
> }
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1872,8 +1872,10 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
> error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg,
> PageTransHuge(page));
> if (error) {
> - if (vmf && PageTransHuge(page))
> + if (vmf && PageTransHuge(page)) {
> count_vm_event(THP_FAULT_FALLBACK);
> + count_vm_event(THP_FAULT_FALLBACK_CHARGE);
> + }
> goto unacct;
> }
> error = shmem_add_to_page_cache(page, mapping, hindex,
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1254,6 +1254,7 @@ const char * const vmstat_text[] = {
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> "thp_fault_alloc",
> "thp_fault_fallback",
> + "thp_fault_fallback_charge",
> "thp_collapse_alloc",
> "thp_collapse_alloc_failed",
> "thp_file_alloc",
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2020-02-19 8:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 5:41 [patch] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-02-18 8:26 ` Kirill A. Shutemov
2020-02-19 1:59 ` David Rientjes
2020-02-18 9:34 ` Mike Rapoport
2020-02-19 2:29 ` [patch 1/2] mm, shmem: add thp fault alloc and fallback stats David Rientjes
2020-02-19 2:29 ` [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-02-19 8:23 ` Mike Rapoport [this message]
2020-02-19 3:22 ` [patch 1/2] mm, shmem: add thp fault alloc and fallback stats Yang Shi
2020-02-19 3:44 ` David Rientjes
2020-02-19 17:01 ` Yang Shi
2020-02-20 13:12 ` Kirill A. Shutemov
2020-03-06 17:23 ` Yang Shi
2020-03-06 21:27 ` David Rientjes
2020-03-06 22:22 [patch 1/2] mm, shmem: add vmstat for hugepage fallback David Rientjes
2020-03-06 22:22 ` [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-03-07 4:13 ` Yang Shi
2020-03-09 15:48 ` Kirill A. Shutemov
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