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Date: Thu, 22 Dec 2011 15:24:33 -0800 From: Tejun Heo <tj@...nel.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: avi@...hat.com, nate@...nel.net, cl@...ux-foundation.org, oleg@...hat.com, axboe@...nel.dk, vgoyal@...hat.com, linux-kernel@...r.kernel.org Subject: Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock Hello, On Thu, Dec 22, 2011 at 03:16:49PM -0800, Andrew Morton wrote: > > The ones allocated in the last patch. blk_group_cpu_stats. > > What last patch. > > I can find no occurence of "blk_group_cpu_stats" on linux-kernel or in > the kernel tree. Sorry it's blkio_group_stats_cpu. It's in the seventh path in this series. > > The stats are per cgroup - request_queue pair. We don't want to > > allocate for all of them for each combination as there are > > configurations with stupid number of request_queues and silly many > > cgroups and #cgroups * #request_queue * #cpus can be huge. So, we > > want on-demand allocation. While the stats are important, they are > > not critical and allocations can be opportunistic. If the allocation > > fails this time, we can try it for the next time. > > Without code to look at I am at a loss. block/blk-cgroup.c blk-throttle.c cfq-iosched.c. Have fun. > request_queues are allocated in blk_alloc_queue_node(), which uses > GFP_KERNEL (and also mysteriously takes a gfp_t arg). Yeah, sure, we *can* allocate everything for every combination when either request_queue or cgroup comes up. That's the thing I tried to explain in the above quoted paragraph. Thanks. -- tejun -- 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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