[lttng-dev] [RFC v2] Add kmalloc failover to vmalloc
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Thu Sep 21 18:52:13 UTC 2017
----- On Sep 21, 2017, at 2:43 PM, Michael Jeanson mjeanson at efficios.com wrote:
> On 2017-09-21 14:39, Mathieu Desnoyers wrote:
>> ----- On Sep 21, 2017, at 2:29 PM, Michael Jeanson mjeanson at efficios.com wrote:
>>
>>> This patch is based on the kvmalloc helpers introduced in kernel 4.12.
>>>
>>> It will gracefully failover memory allocations of more than one page to
>>> vmalloc for systems under high memory pressure or fragmentation.
>>>
>>> I only used it in lttng-events.c as a POC, most allocations fit into a
>>> single page so I'm not sure how useful this actually is.
>>>
>>> Thoughts?
>>
>> Just update the changelog to specify why we need this for struct lttng_session
>> (~32kB), and you can submit it for good with a "Fix: " tag.
>
> I'm not sure it should be a fix, for this to be of any use all the other
> allocations bigger than PAGE_SIZE should also use it. Otherwise, the
> session allocation will succeed but the next sizeable allocation will
> still fail.
What other allocations larger than PAGE_SIZE using kmalloc did you spot ?
Thanks,
Mathieu
>
>>
>> Thanks,
>>
> > Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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