From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 17 May 2001 16:19:35 -0300 (BRST) From: Rik van Riel Subject: Re: SMP/highmem problem In-Reply-To: <20010517203933.F6360@vestdata.no> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN Content-Transfer-Encoding: 8BIT Sender: owner-linux-mm@kvack.org Return-Path: To: =?iso-8859-1?Q?Ragnar_Kj=F8rstad?= Cc: linux-mm@kvack.org, tlan@stud.ntnu.no List-ID: On Thu, 17 May 2001, [iso-8859-1] Ragnar Kjorstad wrote: > I've run into a performance issue. > I use a single process, bonnie++, that creates 16 1 GB files. > However, after a while, the machine gets really unresponsive > and the load gets really high. According to top, all CPU power > is spent in the kernel, mainly on kswapd, bdflush and kupdated. This is at least partly due to the following things: 1) balance_dirty_state() tests for a condition bdflush may not be able to resolve 2) nr_free_buffer_pages() counts free highmem pages, which cannot be allocated to buffer memory, as available; this means that bonnie++ never gets to slow down to disk speed and fills up all of low memory 3) because of 2) kswapd and bdflush are trying to write the data out to disk like crazy, but can never keep up with bonnie++ 4) bonnie++ tries to allocate new pages all the time, but cannot succeed because all of low memory is full of dirty page cache data .. this means it loops in __alloc_pages() and continuously wakes up kswapd and bdflush A few fixes for this situation have gone into 2.4.5-pre2 and 2.4.5-pre3. If you have the time, could you test if this problem has gotten less or has gone away in the latest kernels ? thanks, Rik -- Virtual memory is like a game you can't win; However, without VM there's truly nothing to lose... http://www.surriel.com/ http://distro.conectiva.com/ Send all your spam to aardvark@nl.linux.org (spam digging piggy) -- 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/