From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from localhost (localhost [127.0.0.1]) by mail2.syneticon.net (Postfix) with ESMTP id A58894FE20 for ; Fri, 9 Feb 2007 18:08:34 +0100 (CET) Received: from mail2.syneticon.net ([127.0.0.1]) by localhost (linux [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 18533-13 for ; Fri, 9 Feb 2007 18:08:20 +0100 (CET) Received: from postfix1.syneticon.net (postfix1.syneticon.net [192.168.112.6]) by mail2.syneticon.net (Postfix) with ESMTP for ; Fri, 9 Feb 2007 18:08:19 +0100 (CET) Received: from localhost (filter1.syneticon.net [192.168.113.3]) by postfix1.syneticon.net (Postfix) with ESMTP id 2920D95EF for ; Fri, 9 Feb 2007 18:08:21 +0100 (CET) Received: from postfix1.syneticon.net ([192.168.113.4]) by localhost (192.168.113.3 [192.168.113.3]) (amavisd-new, port 10025) with ESMTP id iTLvjevCJE3G for ; Fri, 9 Feb 2007 18:08:14 +0100 (CET) Received: from [84.44.195.93] (xdsl-84-44-195-93.netcologne.de [84.44.195.93]) by postfix1.syneticon.net (Postfix) with ESMTP for ; Fri, 9 Feb 2007 18:08:14 +0100 (CET) Message-ID: <45CCAA7B.5070805@wpkg.org> Date: Fri, 09 Feb 2007 18:08:11 +0100 From: Tomasz Chmielewski MIME-Version: 1.0 Subject: does SCSI eat my PC's memory? Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: Does SCSI eat my PC's memory? Probably not, but I can't find an explanation of what uses so much RAM when I use SCSI disks. A little background first. Overall, the system has 1 GB memory. When it boots and everything has started, about 60 MB of memory is used (excluding buffers). One partition is on a iscsi target (I access it using open-iscsi): /dev/sda 570G 402G 139G 75% /mnt/iscsi_backup It contains lots of data, many files, hardlinked multiple times (in total, almost 100 000 000 files). When I run "find /mnt/iscsi_backup" for some time, and run "free" to see memory usage, I can see almost 500 MB is used (excluding buffers/cache): # free total used free shared buffers cached Mem: 1048576 1029360 19216 0 530972 17628 -/+ buffers/cache: 480760 567816 Swap: 1048568 68 1048500 Also, stopping all deamons and dropping cache doesn't help (sum of the memory used by all processes, displayed by "ps", is about 60 MB): # echo 1 > /proc/sys/vm/drop_caches # free total used free shared buffers cached Mem: 1048576 453932 594644 0 352 6408 -/+ buffers/cache: 447172 601404 Swap: 1048568 68 1048500 A single "umount" command releases almost 400 MB of memory: # umount /mnt/iscsi_backup/ # free total used free shared buffers cached Mem: 1048576 64188 984388 0 232 6528 -/+ buffers/cache: 57428 991148 Swap: 1048568 64 1048504 What used almost 400 MB? SCSI buffers? I noticed that when I add RAM to the system, more "unexplained" RAM will be used. When I remove some RAM, "unexplained" RAM usage will drop - as a rule of thumb, I observed that about 50% of RAM is used by something I can't identify. -- Tomasz Chmielewski http://wpkg.org -- 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-mm.org/ . Don't email: email@kvack.org