Messages in this thread | | | Date | Fri, 11 Oct 2013 08:28:54 -0600 | From | Jens Axboe <> | Subject | Re: [patch 4/4] blk-mq: switch to percpu-ida for tag menagement |
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On 10/11/2013 01:18 AM, Shaohua Li wrote: > Using percpu-ida to manage blk-mq tags. the percpu-ida has similar algorithm > like the blk-mq-tag. The difference is when a cpu can't allocate tags > blk-mq-tag uses ipi to purge remote cpu cache and percpu-ida directly purges > remote cpu cache. In practice (testing null_blk), the percpu-ida approach is > much faster when total tags aren't enough.
I'm not surprised it's a lot faster the the pathological case of needing to prune tags, the IPI isn't near ideal for that. I'm assuming the general performance is the same for the non-full case?
-- Jens Axboe
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