Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755963Ab0DOA5L (ORCPT ); Wed, 14 Apr 2010 20:57:11 -0400 Received: from smtp-out.google.com ([216.239.44.51]:57828 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753410Ab0DOA5J convert rfc822-to-8bit (ORCPT ); Wed, 14 Apr 2010 20:57:09 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding:x-system-of-record; b=OshNMPvQQ52gYqsbRTfYohez1ErSH7FIP3tqzyutuaSrOEQNGbcu0STNnkyA83TUc tFbP2GEjL5PUdC+ua8QtQ== MIME-Version: 1.0 In-Reply-To: <4BC65E7C.5080203@kernel.org> References: <4BC65E7C.5080203@kernel.org> Date: Wed, 14 Apr 2010 17:57:04 -0700 Message-ID: Subject: Re: [PATCH] 2.6.34-rc3 Disable R_OK (Early ACK) on SII 3726/4726 PMP From: Grant Grundler To: Tejun Heo Cc: Linux IDE mailing list , Jeff Garzik , LKML Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2396 Lines: 77 On Wed, Apr 14, 2010 at 5:31 PM, Tejun Heo wrote: > Hello, > > On 04/14/2010 09:46 AM, Grant Grundler wrote: >> In 2009, While running "cache read" performance test of drives behind >> SII PMP we encountered a "all 5 drives" timeout on more than 30% of the >> machines under test.  This patch reduces the rate by a factor of about 70. >> Low enough that we didn't care to further investigate the issue. > > Interesting. > >> Performance impact with any sort of "normal" use was ~2%+ CPU and less >> than 1% throughput degradation.  Worst case impact (cached read) was >> 6% IOPS reduction. This is with NCQ off (q=1) but I believe FIS based >> switching enabled in the SATA driver. > > Given the general flakiness of the device, I'm more than willing to > pay some overhead for stability and the performance hit seems pretty > small. > >> @@ -260,12 +262,28 @@ static int sata_pmp_configure(struct ata_device >> *dev, int print_info) >>                 goto fail; >>         } >> >> +       /* For Sil3726, disable sending Early R_OK */ >> +       if (vendor == 0x1095 && devid == 0x3726) { > > Isn't this also applicable to 4723 and 4726? Sorry, I don't know why I included 4726 in the Subject line since I only tested with 3726. I expect it would apply to 4726 but someone who knows the internals of both would have to confirm that. I don't know anything about 4723. > >> diff --git a/include/linux/ata.h b/include/linux/ata.h >> index 700c5b9..18fc208 100644 >> --- a/include/linux/ata.h >> +++ b/include/linux/ata.h >> @@ -386,6 +386,7 @@ enum { >>         SATA_PMP_GSCR_ERROR_EN  = 33, >>         SATA_PMP_GSCR_FEAT      = 64, >>         SATA_PMP_GSCR_FEAT_EN   = 96, >> +       SATA_PMP_GSCR_SII_POL   = 129,  /* VENDOR : Silicon Image 3726/4726 */ > > Can you plesae define it inside libata-pmp.c? Yes. I'll resubmit with "SII_POL" defined "locally". > ata.h only contains stuff defined by the ATA standard. Ah ok. I didn't realize that. > > Other than the above nitpicks, > > Acked-by: Tejun Heo Thanks for the Ack/Review! grant > > Thanks. > > -- > tejun > -- 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/