Re: [dpdk-dev] [PATCH v2] mempool: fix slow allocation of large mempools

[Thomas Monjalon <thomas@monjalon.net>]

17/01/2020 11:09, Andrew Rybchenko:
> On 1/17/20 1:01 PM, Olivier Matz wrote:
> > On Fri, Jan 17, 2020 at 10:51:49AM +0100, Olivier Matz wrote:
> >> When allocating a mempool which is larger than the largest
> >> available area, it can take a lot of time:
> >>
> >> a- the mempool calculate the required memory size, and tries
> >>    to allocate it, it fails
> >> b- then it tries to allocate the largest available area (this
> >>    does not request new huge pages)
> >> c- add this zone to the mempool, this triggers the allocation
> >>    of a mem hdr, which request a new huge page
> >> d- back to a- until mempool is populated or until there is no
> >>    more memory
> >>
> >> This can take a lot of time to finally fail (several minutes): in step
> >> a- it takes all available hugepages on the system, then release them
> >> after it fails.
> >>
> >> The problem appeared with commit eba11e364614 ("mempool: reduce wasted
> >> space on populate"), because smaller chunks are now allowed. Previously,
> >> it had to be at least one page size, which is not the case in step b-.
> >>
> >> To fix this, implement our own way to allocate the largest available
> >> area instead of using the feature from memzone: if an allocation fails,
> >> try to divide the size by 2 and retry. When the requested size falls
> >> below min_chunk_size, stop and return an error.
> >>
> >> Fixes: eba11e364614 ("mempool: reduce wasted space on populate")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> > 
> > Sorry I forgot to report Anatoly's ack on v1
> > http://patchwork.dpdk.org/patch/64370/
> > 
> > Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
> 
> Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>

Applied, thanks