lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 12 Apr 2019 13:07:17 -0700
From:   Shakeel Butt <>
To:     Johannes Weiner <>
Cc:     Andrew Morton <>,
        Linux MM <>,
        Cgroups <>,
        LKML <>,
Subject: Re: [PATCH 0/4] mm: memcontrol: memory.stat cost & correctness

On Fri, Apr 12, 2019 at 8:15 AM Johannes Weiner <> wrote:
> The cgroup memory.stat file holds recursive statistics for the entire
> subtree. The current implementation does this tree walk on-demand
> whenever the file is read. This is giving us problems in production.
> 1. The cost of aggregating the statistics on-demand is high. A lot of
> system service cgroups are mostly idle and their stats don't change
> between reads, yet we always have to check them. There are also always
> some lazily-dying cgroups sitting around that are pinned by a handful
> of remaining page cache; the same applies to them.
> In an application that periodically monitors memory.stat in our fleet,
> we have seen the aggregation consume up to 5% CPU time.
> 2. When cgroups die and disappear from the cgroup tree, so do their
> accumulated vm events. The result is that the event counters at
> higher-level cgroups can go backwards and confuse some of our
> automation, let alone people looking at the graphs over time.
> To address both issues, this patch series changes the stat
> implementation to spill counts upwards when the counters change.
> The upward spilling is batched using the existing per-cpu cache. In a
> sparse file stress test with 5 level cgroup nesting, the additional
> cost of the flushing was negligible (a little under 1% of CPU at 100%
> CPU utilization, compared to the 5% of reading memory.stat during
> regular operation).

For whole series:

Reviewed-by: Shakeel Butt <>

>  include/linux/memcontrol.h |  96 +++++++-------
>  mm/memcontrol.c            | 290 +++++++++++++++++++++++++++----------------
>  mm/vmscan.c                |   4 +-
>  mm/workingset.c            |   7 +-
>  4 files changed, 234 insertions(+), 163 deletions(-)

Powered by blists - more mailing lists