linux-kernel - Re: [PATCH 1/1] libata: Get rid of ata_port::qc

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Date:	Tue, 11 Feb 2014 09:40:40 +0100
From:	Alexander Gordeev <agordeev@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
Subject: Re: [PATCH 1/1] libata: Get rid of ata_port::qc_allocated bitmask

On Tue, Jan 21, 2014 at 04:02:26PM +0100, Alexander Gordeev wrote:
> Scanning ata_port::qc_allocated bitmask for free tags has
> been a performance bottleneck due to the cache line bouncing.
> This update replaces ata_port::qc_allocated bitmask with
> optimized for parallel access percpu_ida tags allocator.

Hi Tejun,

There is a discussion about imperfect percpu_ida handling of low nr of tags.
I think this change is too early to bring.

Thanks!

-- 
Regards,
Alexander Gordeev
agordeev@...hat.com
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