Messages in this thread | | | Date | Tue, 11 Jul 2017 13:22:04 -0400 | From | Johannes Weiner <> | Subject | Re: [PATCH] tracing/ring_buffer: Try harder to allocate |
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On Mon, Jul 10, 2017 at 11:05:00PM -0700, Joel Fernandes wrote: > ftrace can fail to allocate per-CPU ring buffer on systems with a large > number of CPUs coupled while large amounts of cache happening in the > page cache. Currently the ring buffer allocation doesn't retry in the VM > implementation even if direct-reclaim made some progress but still > wasn't able to find a free page. On retrying I see that the allocations > almost always succeed. The retry doesn't happen because __GFP_NORETRY is > used in the tracer to prevent the case where we might OOM, however if we > drop __GFP_NORETRY, we risk destabilizing the system if OOM killer is > triggered. To prevent this situation, use the __GFP_RETRY_MAYFAIL flag > introduced recently [1]. > > Tested the following still succeeds without destabilizing a system with > 1GB memory. > echo 300000 > /sys/kernel/debug/tracing/buffer_size_kb > > [1] https://marc.info/?l=linux-mm&m=149820805124906&w=2 > > Cc: Alexander Duyck <alexander.h.duyck@intel.com> > Cc: Mel Gorman <mgorman@suse.de> > Cc: Hao Lee <haolee.swjtu@gmail.com> > Cc: Vladimir Davydov <vdavydov.dev@gmail.com> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Tim Murray <timmurray@google.com> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: stable@vger.kernel.org > Signed-off-by: Joel Fernandes <joelaf@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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