From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 12 Jun 2000 13:50:58 -0400 (EDT) From: "Benjamin C.R. LaHaise" Subject: [Fwd] VMM swap interactive performance Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: 8BIT Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: >>From sct@redhat.com Mon Jun 12 13:47:45 2000 Message-ID: <39450E67.7CC8DA89@baldauf.org> Date: Mon, 12 Jun 2000 18:23:03 +0200 From: Xuan Baldauf Organization: Medium.net X-Mailer: Mozilla 4.73 [en] (Win98; I) X-Accept-Language: en,de-DE MIME-Version: 1.0 To: linux-kernel@vger.rutgers.edu Subject: VMM swap interactive performance Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-linux-kernel@vger.rutgers.edu Precedence: bulk X-Loop: majordomo@vger.rutgers.edu Resent-From: sct@redhat.com Resent-Date: Mon, 12 Jun 2000 18:45:23 +0100 Resent-To: linux-mm@kvack.org Return-Path: X-Orcpt: rfc822;linux-mm@kvack.org Hello, since I switched from 2.2.15 to 2.4.0-test-acX (X is currently 12), I noticed a significant but subjective slow down in interactive performance. Under Linux2.2, when I hit some key (I telneted to the box), the reaction (printing the appropriate character) always came promptly, even if the box was busy (seti@home, kernel compile, etc). Normally, you did not "feel" that you use telnet due to latency. But since using 2.4, there are sometimes seconds between hitting the key and printing the result. Now I ran a md5sum (besides a kernel compile and seti) and encountered the same problem, and top showed me this: 6:07pm up 1 day, 23:05, 5 users, load average: 4.84, 3.08, 2.23 77 processes: 73 sleeping, 4 running, 0 zombie, 0 stopped CPU states: 24.1% user, 13.9% system, 0.3% nice, 63.2% idle Mem: 38368K av, 37596K used, 772K free, 0K shrd, 984K buff Swap: 120956K av, 33524K used, 87432K free 18332K cached PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 12183 root 19 0 180 136 108 R 0 29.1 0.3 1:28 md5sum 2 root 1 0 0 0 0 DW 0 1.8 0.0 3:26 kswapd 12283 root 2 0 848 848 656 R 0 1.7 2.2 0:00 top 1231 root 1 0 1400 624 476 D 0 1.3 1.6 0:35 named 12308 root 0 0 1168 1156 900 S 0 0.5 3.0 0:00 sendmail 12309 root 0 0 1168 1156 900 S 0 0.4 3.0 0:00 sendmail 735 squid 0 0 8596 676 352 S 0 0.3 1.7 9:56 squid 799 seti 12 12 13796 7312 2036 R N 0 0.3 19.0 2574m setiathome I was somewhat... puzzled, because normally linux would use the available resources appropriately, but because the CPU was 63.2% idle, this obviously was wrong. I was used to "overload" the memory with seti and the like, now I have to kill seti in order to have good kernel compile speed. I think the virtual memory management is not optimal for the "memory overload" case. I assume that the kernel swaps out pages too aggressively, making them unavailable in the next second. Does anybody has a ready to run swap-benchmark program? I'd like to run it and prove the difference. Xuan. :o) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/ -- 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/