Quoting Frederic Crozat (fcro...@suse.com):
>
> Le lundi 04 février 2013 à 08:38 -0600, Serge Hallyn a écrit :
> > Quoting Gary Ballantyne (gary.ballant...@haulashore.com):
> > > On Fri, 1 Feb 2013 10:24:13 -0600
> > > Serge Hallyn <serge.hal...@canonical.com> wrote:
> > >
> > > >
> > > > Did you actually test with a memory hog program? I just noticed there
> > > > appears to be a bug in that if I
> > > >
> > > > d=/sys/fs/cgroup/memory/a
> > > > mkdir $d
> > > > echo 1 > $d/memory.use_hierarchy
> > > > echo 5000 > $d/memory.limit_in_bytes
> > > > mkdir $d/b
> > > >
> > > > then $d/b/memory.limit_in_bytes does not report the reduced limit.
> > > > However
> > > > whenI run a program which does char *c = malloc(10000) after doing
> > > > echo $$ > $d/b/tasks
> > > >
> > > > then I get killed by OOM.
> > > >
> > > > -serge
> > >
> > > I tested with a large array in ipython. Though, from your example, it
> > > seems I'm missing memory.use_hierarchy.
> > >
> > > In principle, it seems like I need something like:
> > >
> > > echo 1 > /sys/fs/cgroup/memory/lxc/memory.use_hierarchy
> > >
> > > But, I can't do that before the container is started (no lxc directory)
> > > or after it is started (device busy).
> > >
> >
> > Yup, it looks like lxc ought to set that at startup. I can think of
> > absolutely no cases where we would *not* want that done. Something
> > like:
> >
> > Subject: [PATCH 1/1] Try to enable memory cgroup use_hierarchy option.
> >
> > The memory cgroup has a 'memory.use_hierarchy' which is initialized to
> > 0. It needs to be set to 1 at our top level, that is
> > /sys/fs/cgroup/memory/lxc/memory.use_hiararchy, before we create any
> > containers. After the fact is too late.
> >
> > Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
>
> Any reason this patch was not pushed ?
>
> After fixing it a bit (it was missing some directory creation and needed some
> massage), it works as expected on 0.8.0
> and it prevents kernel warning about memcgroup use_hierarchy warning.
>
> New version (for 0.8.0) attached.
>
>
> --
> Frederic Crozat <fcro...@suse.com>
> SUSE
>
> --
> Frederic Crozat <fcro...@suse.com>
> SUSE
> Date: Mon, 4 Feb 2013 08:38:19 -0600
> From: Serge Hallyn <serge.hal...@canonical.com>
> Subject: [PATCH 1/1] Try to enable memory cgroup use_hierarchy option.
>
> The memory cgroup has a 'memory.use_hierarchy' which is initialized to
> 0. It needs to be set to 1 at our top level, that is
> /sys/fs/cgroup/memory/lxc/memory.use_hiararchy, before we create any
> containers. After the fact is too late.
>
> Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
> ---
> src/lxc/cgroup.c | 41 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> Index: lxc-0.8.0/src/lxc/cgroup.c
> ===================================================================
> --- lxc-0.8.0.orig/src/lxc/cgroup.c
> +++ lxc-0.8.0/src/lxc/cgroup.c
> @@ -356,6 +356,52 @@ int try_to_move_cgname(char *cgparent, c
> }
>
> /*
> + * The memory cgroup has a 'memory.use_hierarchy' which is initialized to
> + * 0. It needs to be set to 1 at our top level, that is
> + * /sys/fs/cgroup/memory/lxc/memory.use_hierarchy, before we create any
> + * containers. After the fact is too late.
> + */
> +static int enable_hierarchy(char *path)
> +{
> + char filepath[MAXPATHLEN];
> + int ret;
> + FILE *f;
> + int len = strlen(path);
> +
> + if (strlen(path) < 15 || strncmp(path+15, "memory",6) != 0)
> + return 0;
> +
> + ret = snprintf(filepath, MAXPATHLEN, "%s/memory.use_hierarchy", path);
> + if (ret < 0 || ret >= MAXPATHLEN) {
> + SYSERROR("Failed creating memory hierarchy filepath name");
> + return -1;
> + }
Thanks - clearly my patch needed some love :) Just a few comments below.
> +
> + /* check if directory exists, and create it otherwise */
> + if (access(path, F_OK)) {
> + ret = mkdir(path, 0755);
> + if (ret == -1 && errno == EEXIST) {
Did you mean errno != EEXIST?
> + SYSERROR("failed to create '%s' directory", path);
> + return -1;
> + }
> + }
> +
> + f = fopen(filepath, "w");
> + if (!f) {
> + /* kernel may not support this file - s'ok */
> + WARN("Unable to open cgroup memory.use_hierarchy file");
> + return 0;
> + }
> +
> + if (fprintf(f, "1") < 1) {
> + WARN("Unable to set hierarchy to true for memory cgroup");
> + }
> + fclose(f);
> +
> + return 0;
> +}
> +
> +/*
> * create a cgroup for the container in a particular subsystem.
> */
> static int lxc_one_cgroup_create(const char *name,
> @@ -384,6 +430,10 @@ static int lxc_one_cgroup_create(const c
> SYSERROR("Failed creating pathname for cgroup parent (%d)\n",
> ret);
> return -1;
> }
> +
> + if (enable_hierarchy(cgparent))
> + return -1;
Hm, do we want to fail container start on that, or just log a warning?
> +
> ret = snprintf(cgname, MAXPATHLEN, "%s/%s", cgparent, name);
> if (ret < 0 || ret >= MAXPATHLEN) {
> SYSERROR("Failed creating pathname for cgroup (%d)\n", ret);
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