From: Tejun Heo <htejun@gmail.com>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: linux-ide@vger.kernel.org, jeff@garzik.org
Subject: Re: [PATCH] libata: get rid of ATA_MAX_QUEUE loop in ata_qc_complete_multiple()
Date: Wed, 20 May 2009 16:26:05 +0900 [thread overview]
Message-ID: <4A13B08D.3060005@gmail.com> (raw)
In-Reply-To: <20090520065752.GC11363@kernel.dk>
Hello, Jens.
Jens Axboe wrote:
> @@ -5039,16 +5039,19 @@ int ata_qc_complete_multiple(struct ata_port *ap, u32 qc_active)
> return -EINVAL;
> }
>
> - for (i = 0; i < ATA_MAX_QUEUE; i++) {
> + while (done_mask) {
> struct ata_queued_cmd *qc;
> + unsigned int next = __ffs(done_mask);
>
> - if (!(done_mask & (1 << i)))
> - continue;
> -
> - if ((qc = ata_qc_from_tag(ap, i))) {
> + qc = ata_qc_from_tag(ap, i + next);
> + if (qc) {
> ata_qc_complete(qc);
> nr_done++;
> }
> + if (++next >= ATA_MAX_QUEUE)
> + break;
Given that __ffs doesn't care how far the first bit is on most archs
(even the generic one), I think it would be simpler and more efficient
to simply do done_mask &= ~(1 << i) and loop without adding to index
and shifting.
Thanks.
--
tejun
next prev parent reply other threads:[~2009-05-20 7:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-20 6:57 [PATCH] libata: get rid of ATA_MAX_QUEUE loop in ata_qc_complete_multiple() Jens Axboe
2009-05-20 7:26 ` Tejun Heo [this message]
2009-05-20 7:40 ` Jens Axboe
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