Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754374AbYJVHk6 (ORCPT ); Wed, 22 Oct 2008 03:40:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752138AbYJVHkc (ORCPT ); Wed, 22 Oct 2008 03:40:32 -0400 Received: from pasmtpb.tele.dk ([80.160.77.98]:57795 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752073AbYJVHka (ORCPT ); Wed, 22 Oct 2008 03:40:30 -0400 From: Jens Axboe To: linux-ide@vger.kernel.org Cc: linux-kernel@vger.kernel.org, tj@kernel.org, jeff@garzik.org, Jens Axboe Subject: [PATCH 1/2] libata: get rid of ATA_MAX_QUEUE loop in ata_qc_complete_multiple() Date: Wed, 22 Oct 2008 09:40:42 +0200 Message-Id: <1224661243-7929-2-git-send-email-jens.axboe@oracle.com> X-Mailer: git-send-email 1.6.0.2.588.g3102 In-Reply-To: <1224661243-7929-1-git-send-email-jens.axboe@oracle.com> References: <1224661243-7929-1-git-send-email-jens.axboe@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1628 Lines: 58 We very rarely (if ever) complete more than one command in the sactive mask at the time, even for extremely high IO rates. So looping over the entire range of possible tags is pointless, instead use __ffs() to just find the completed tags directly. Signed-off-by: Jens Axboe --- drivers/ata/libata-core.c | 15 +++++++++------ 1 files changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 1ee9499..c3c53e7 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -4799,9 +4799,9 @@ void ata_qc_complete(struct ata_queued_cmd *qc) */ int ata_qc_complete_multiple(struct ata_port *ap, u32 qc_active) { + unsigned int i = 0; int nr_done = 0; u32 done_mask; - int i; done_mask = ap->qc_active ^ qc_active; @@ -4811,16 +4811,19 @@ 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; + i += next; + done_mask >>= next; } return nr_done; -- 1.6.0.2.588.g3102 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/