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Message-ID: <4ED36A6D.60900@parallels.com> Date: Mon, 28 Nov 2011 09:03:09 -0200 From: Glauber Costa <glommer@...allels.com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> CC: <linux-kernel@...r.kernel.org>, <lizf@...fujitsu.com>, <ebiederm@...ssion.com>, <davem@...emloft.net>, <paul@...lmenage.org>, <gthelen@...gle.com>, <netdev@...r.kernel.org>, <linux-mm@...ck.org>, <kirill@...temov.name>, <avagin@...allels.com>, <devel@...nvz.org>, <eric.dumazet@...il.com>, <cgroups@...r.kernel.org> Subject: Re: [PATCH v6 01/10] Basic kernel memory functionality for the Memory Controller On 11/28/2011 12:24 AM, KAMEZAWA Hiroyuki wrote: > On Fri, 25 Nov 2011 15:38:07 -0200 > Glauber Costa<glommer@...allels.com> wrote: > >> This patch lays down the foundation for the kernel memory component >> of the Memory Controller. >> >> As of today, I am only laying down the following files: >> >> * memory.independent_kmem_limit >> * memory.kmem.limit_in_bytes (currently ignored) >> * memory.kmem.usage_in_bytes (always zero) >> >> Signed-off-by: Glauber Costa<glommer@...allels.com> >> Reviewed-by: Kirill A. Shutemov<kirill@...temov.name> >> CC: Paul Menage<paul@...lmenage.org> >> CC: Greg Thelen<gthelen@...gle.com> >> --- >> Documentation/cgroups/memory.txt | 36 ++++++++++++- >> init/Kconfig | 14 +++++ >> mm/memcontrol.c | 107 ++++++++++++++++++++++++++++++++++++-- >> 3 files changed, 150 insertions(+), 7 deletions(-) >> >> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt >> index 06eb6d9..bf00cd2 100644 >> --- a/Documentation/cgroups/memory.txt >> +++ b/Documentation/cgroups/memory.txt >> @@ -44,8 +44,9 @@ Features: >> - oom-killer disable knob and oom-notifier >> - Root cgroup has no limit controls. >> >> - Kernel memory and Hugepages are not under control yet. We just manage >> - pages on LRU. To add more controls, we have to take care of performance. >> + Hugepages is not under control yet. We just manage pages on LRU. To add more >> + controls, we have to take care of performance. Kernel memory support is work >> + in progress, and the current version provides basically functionality. >> >> Brief summary of control files. >> >> @@ -56,8 +57,11 @@ Brief summary of control files. >> (See 5.5 for details) >> memory.memsw.usage_in_bytes # show current res_counter usage for memory+Swap >> (See 5.5 for details) >> + memory.kmem.usage_in_bytes # show current res_counter usage for kmem only. >> + (See 2.7 for details) >> memory.limit_in_bytes # set/show limit of memory usage >> memory.memsw.limit_in_bytes # set/show limit of memory+Swap usage >> + memory.kmem.limit_in_bytes # if allowed, set/show limit of kernel memory >> memory.failcnt # show the number of memory usage hits limits >> memory.memsw.failcnt # show the number of memory+Swap hits limits >> memory.max_usage_in_bytes # show max memory usage recorded >> @@ -72,6 +76,9 @@ Brief summary of control files. >> memory.oom_control # set/show oom controls. >> memory.numa_stat # show the number of memory usage per numa node >> >> + memory.independent_kmem_limit # select whether or not kernel memory limits are >> + independent of user limits >> + >> 1. History >> >> The memory controller has a long history. A request for comments for the memory >> @@ -255,6 +262,31 @@ When oom event notifier is registered, event will be delivered. >> per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by >> zone->lru_lock, it has no lock of its own. >> >> +2.7 Kernel Memory Extension (CONFIG_CGROUP_MEM_RES_CTLR_KMEM) >> + >> + With the Kernel memory extension, the Memory Controller is able to limit >> +the amount of kernel memory used by the system. Kernel memory is fundamentally >> +different than user memory, since it can't be swapped out, which makes it >> +possible to DoS the system by consuming too much of this precious resource. >> +Kernel memory limits are not imposed for the root cgroup. >> + >> +Memory limits as specified by the standard Memory Controller may or may not >> +take kernel memory into consideration. This is achieved through the file >> +memory.independent_kmem_limit. A Value different than 0 will allow for kernel >> +memory to be controlled separately. >> + >> +When kernel memory limits are not independent, the limit values set in >> +memory.kmem files are ignored. >> + >> +Currently no soft limit is implemented for kernel memory. It is future work >> +to trigger slab reclaim when those limits are reached. >> + >> +CAUTION: As of this writing, the kmem extention may prevent tasks from moving >> +among cgroups. If a task has kmem accounting in a cgroup, the task cannot be >> +moved until the kmem resource is released. Also, until the resource is fully >> +released, the cgroup cannot be destroyed. So, please consider your use cases >> +and set kmem extention config option carefully. >> + > > This seems that memcg 'has' kernel memory limiting feature for all kinds of kmem.. > Could you add a list of "currently controled kmems" section ? > And update the list in later patch ? > > Thanks, > -Kame > > Hi Kame, Thanks for your review. Since none of your comments are blockers, I'd prefer to send follow up patches if you don't mind - assuming Dave won't have any restrictions himself that would prevent him from picking this series. If I have to resend it anyway, I'll be more than happy to address them all in my next submission -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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