From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 30 Dec 2000 19:16:39 +0100 From: Andrea Arcangeli Subject: Re: 2.2.19pre3 and poor reponse to RT-scheduled processes? Message-ID: <20001230191639.E9332@athlon.random> References: <20001229161927.A560@xi.linuxpower.cx> <200012292154.QAA17527@ninigret.metatel.office> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200012292154.QAA17527@ninigret.metatel.office>; from rafal.boni@eDial.com on Fri, Dec 29, 2000 at 04:54:23PM -0500 Sender: owner-linux-mm@kvack.org Return-Path: To: Rafal Boni Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Gregory Maxwell List-ID: On Fri, Dec 29, 2000 at 04:54:23PM -0500, Rafal Boni wrote: > Now my box behaves much more reasonably... I'll just have to beat harder > on it and see what happens. Another thing: while writing to disk if you want low latency readers you can do: elvtune -r 1 /dev/hd[abcd] The 1/2 seconds stalls you see could be just because of applications that waits I/O synchronously while the elevator is reodering I/O requests (and even if the elevator wouldn't reorder anything the new requests would go to the end of the I/O queue so they would have some higher latency anyways). That's normal and if it's the case to avoid those stalls you can only decrease the I/O load or increase disk throughput ;). The important thing is that the kernel is not sitting in a tight kernel loop without reschedule in it during such 2 seconds. However 2.2.19pre3aa4 includes also the lowlatency bugfixes in case you have tons of ram and you're sending huge buffers to syscalls. Andrea -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/