[lttng-dev] [RFC v2] Add kmalloc failover to vmalloc

[Michael Jeanson]

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.

> 
> Thanks,
> 
> Mathieu