On Sat, Jan 13, 2007 at 03:30:27PM +0100, Willy Tarreau wrote: > On Sat, Jan 13, 2007 at 02:16:01PM +0100, Toon van der Pas wrote: > > On Sat, Jan 13, 2007 at 08:22:18AM +0100, Willy Tarreau wrote: > > > > > > > > Which makes me think that we aren't writing back fast enough. If I > > > > mount the drive "sync" the issue clearly goes away. > > > > > > > > It appears from an strace we are doing ftruncate64(5, 178257920) when > > > > we OOM. > > > > > > > > Any ideas on VM parameters to tweak so we throttle this from occurring? > > > > > > Take a look at /proc/sys/vm/bdflush. There are several useful parameters > > > there (doc is in linux-xxx/Documentation). For instance, the first column > > > is the percentage of memory used by writes before starting to write on > > > disk. When using tcpdump intensively, I lower this one to about 1%. > > > > Hi Willy, > > > > I know you're doing a great job on keeping the 2.4 kernel in shape, > > but do you also have a good advice for people with more recent > > kernels? (hint: the file /proc/sys/vm/bdflush is missing) > > OK OK OK... Next time I will have coffee *before* replying :-) > > Check /proc/sys/vm/dirty_ratio and dirty_background_ratio. Both are > percentage of total memory. The first one is for "foreground" writes > (ie the writing process may block) while the second one is for > "background" writes : > > $ uname -a > Linux hp 2.6.16-rc2-pa1 #1 Fri Feb 3 23:34:56 MST 2006 parisc unknown > $ cat /proc/sys/vm/dirty_ratio > 40 > $ cat /proc/sys/vm/dirty_background_ratio > 10 > > Again, lowering those values should help writing data to disk > sooner. Also you should take a look at min_free_kbytes (although > I've not played with it yet) :
Ahh, okay, I didn't really understand these parameters before. Now I think I understand what they are supposed to do. I'll do some experiments with them. Thanks for your help. Toon. BTW: That's pretty exotic hardware you have there (parisc). ;-) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
