Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 10 Oct 2001 12:15:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Oct 2001 12:14:51 -0400 Received: from c009-h019.c009.snv.cp.net ([209.228.34.132]:7577 "HELO c009.snv.cp.net") by vger.kernel.org with SMTP id ; Wed, 10 Oct 2001 12:14:37 -0400 X-Sent: 10 Oct 2001 16:15:02 GMT Date: Wed, 10 Oct 2001 09:16:13 -0700 (PDT) From: "Jeffrey W. Baker" X-X-Sender: To: Subject: seq i/o kills all kernels Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I just did some more testing with 2.4.10-ac10, 2.4.10-ac10-eatcache, and 2.4.11. Fast sequential i/o on any of these kernels makes the system stop doing anything else. On 2.4.10-ac10 and 2.4.10-ac10-eatcache, the performance is the same. I start a mmap i/o process that reads and writes 16MB blocks in a 1GB file. This proceeds at about 20MB/s while nothing else is running. XMMS is undisturbed by this activity. Then, I start dd if=/dev/zero of=bigfile bs=32k count=32768. This proceeds at 40MB/s but XMMS stops completely and the mmap i/o rate at the same time fals to about 100KB/s. Essentially no other process makes progress while the dd is running. The system is unusable. On 2.4.11, XMMS skips[1] but the mmap i/o continues to make progress at about 5MB/s. The dd proceeds as well, slightly slower than under 2.4.10-ac10[-eatcache]. Interactive behavior is abyssmal. The machine is 1.4GHz Athlon, 256MB main memory, software RAID-1 on aic7xxx. No, I haven't tried preemptible kernel yet. -jwb [1] Skipping is a gentle term. XMMS plays 10ms bursts every 5-10 seconds. - 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/