On Thu 22-09-16 11:30:36, Janani Ravichandran wrote:

quoted

On Sep 19, 2016, at 5:42 AM, Michal Hocko [off-list ref] wrote:

On Tue 13-09-16 14:04:49, Janani Ravichandran wrote:

quoted

quoted

On Sep 12, 2016, at 8:16 AM, Michal Hocko [off-list ref] wrote:

Ia??m using the function graph tracer to see how long __alloc_pages_nodemask()
took.

How can you map the function graph tracer to a specif context? Let's say
I would like to know why a particular allocation took so long. Would
that be possible?

Maybe not. If the latencies are due to direct reclaim or memory compaction, you
get some information from the tracepoints (like mm_vmscan_direct_reclaim_begin,
mm_compaction_begin, etc). But otherwise, you dona??t get any context information. 
Function graph only gives the time spent in alloc_pages_nodemask() in that case.

Then I really think that we need a starting trace point. I think that
having the full context information is really helpful in order to
understand latencies induced by allocations.
-- 
Michal Hocko
SUSE Labs

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