Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 2 Apr 2001 15:28:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 2 Apr 2001 15:28:05 -0400 Received: from aslan.scsiguy.com ([63.229.232.106]:25860 "EHLO aslan.scsiguy.com") by vger.kernel.org with ESMTP id ; Mon, 2 Apr 2001 15:27:51 -0400 Message-Id: <200104021926.f32JQxs89810@aslan.scsiguy.com> To: Admin Mailing Lists cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, aic7xxx@FreeBSD.ORG Subject: Re: aic7xxx TCQ settings? In-Reply-To: Your message of "Mon, 02 Apr 2001 15:16:34 EDT." Date: Mon, 02 Apr 2001 13:26:59 -0600 From: "Justin T. Gibbs" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > >I'm using 2.4.3 vanilla with aic7xxx (aic7880 onboard) >I set the max # of TCQ commands per device setting to 50..what's a really >good setting for this, just the default of 253? Depends on the device. The aic7xxx driver will determine the maximum number of tags that a particular device can handle and limit the transactions accordingly. For devices with now hard limit, transactions will be dynamically varied to limit the occurrance of queue full but to otherwise try to keep the limit as high as possible. Some devices do not perform well when lots of transactions are outstanding even though they never report queue full. On these devices, you will get better performance if you lower your transaction settings. > >In /proc/scsi/aic7xxx/0 i see for my drives these numbers: > Commands Queued 140000 This is a count of the number of commands ever queued to the device. The only time it will "decrease" is when the counter wraps to 0. The counter, at least in the 6.1.8 driver, is an unsigned long. > Commands Active 0 This is a count of the number of commands currently outstanding to the device. You system was idle, SCSI wise, when you pulled this information. > Command Openings 253 Current "soft limit" on tagged transactions. We've never seen a queue full from this device, so the tag count has not been reduced from its original setting. > Max Tagged Openings 253 Hard limit on the number of tagged transactions. The hard limit is set by monitoring the device's "queue full" behavior. -- Justin - 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/