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Date: Wed, 19 May 2010 11:27:08 +0200 From: Andi Kleen <ak@...ux.intel.com> To: tim <tim.c.chen@...ux.intel.com> CC: linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/2] tmpfs: Improve tmpfs scalability , tim wrote: > > We created a token jar library implementing > per cpu cache of tokens to avoid lock contentions whenever > we retrieve or return a token to a token jar. Using this library > with tmpfs, we find Aim7 fserver throughput improved 270% > on a 4 socket, 32 cores NHM-EX system. > > In current implementation of tmpfs, whenever we > get a new page, stat_lock in shmem_sb_info needs to be acquired. > This causes a lot of lock contentions when multiple > threads are using tmpfs simultaneously, which makes > system with large number of cpus scale poorly. > Almost 75% of cpu time was spent contending on > stat_lock when we ran Aim7 fserver load with 128 threads > on a 4 socket, 32 cores NHM-EX system. > > The first patch in the series implements the quick token jar. > The second patch update the shmem code of tmpfs to use this > library to improve tmpfs performance. I reviewed both patches and they look good to me. Especially the token jar library should be useful in other places too. Reviewed-by: Andi Kleen <ak@...ux.intel.com> -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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