On Mon, 21 Jan 2002 16:21:30 +0300 Nikita Danilov <[EMAIL PROTECTED]> wrote:
> Bram Stolk writes: > > Hello, > > > > I'm trying to delay the writes to disk. > > > > Normally, this can be achieved by editting > > /proc/sys/vm/bdflush > > > > I believed reiserfs does not use bdflush nor kupdated. > > Looking at the source code, I get the impression that > > the write delay is hard coded to 5 seconds. > > Is this so? > > > > The line of code that makes me think it is hardcoded > > to 5 is this line: > > > > interruptible_sleep_on_timeout(&reiserfs_commit_thread_wait, 5) ; > > Upgrade to the newer kernel, by the way: code line above contains bug > already fixed (interruptible_sleep_on_timeout() takes timeout in jiffies > rather than second). Back to the your question, there is no currently > way to tune this delay. I thought about reusing /proc/sys/vm/bdflush, > but this thing is not available to modules, as Chris Mason pointed > out. Probably our own parameter in /proc, or boot/module parameter is > the right way to go. > > > > > Is there an easy way to have the filesystem delay the writes much longer, > > like an hour or so? > > You will risk loosing a lot of data then, but if you want to do this, losing data is something I can live with. But will less-frequent writing also increase chances of leaving the filesystem in an invalid state? Lost data with an otherwise valid fs is not so bad. > just edit the code. It would be nice if you measured how this impacts > performance. Ok, a code-edit. But is it indeed the '5' value in the interruptible_sleep_on_timeout call? The latest 2.4.* kernel on ftp.funet.fi (2.4.18) contains the same line, also with value '5'. What 'newer kernel' are you talking about? the 2.5 kernel? About performance: it will undoubtedly improve a lot if you only seldom burden the disk with write-ops. It should especially benefit from cases where you repeatedly write the same disk-blocks. Bram > > > > > many thanks, > > > > Bram Stolk > > > > Nikita. -- ------------------------------------------------------------------------------ Bram Stolk, VR Specialist. SARA Academic Computing Services Amsterdam, PO Box 94613, 1090 GP AMSTERDAM email: [EMAIL PROTECTED] Phone +31-20-5923059 Fax +31-20-6683167 "I heard if you play the NT-4.0-CD backwards, you get a satanic message." "Thats nothing, if you play it forward, it installs NT-4.0" ------------------------------------------------------------------------------
