any way to disable fsync?
Hi I got problem with apps that are calling fsync, it makes my hard drive flush like mad and it slows down things quite a lot. Example: I'm using amarok and amrok uses sqlite for storing data, sqlite calls fsync after every write so on song change amarok writes to sqlite some statistic data about what I listen and sqllite calls fsync, now I got amarok trying to load next song and sqlite fsyncing and the problem is that fsyncing under reiser4 is expensive, it takes a lot of time even if I'm only running amarok and nothing else ( I got 4200RPM drive in my notebook so it;s not a speed daemon). I patched sqlite in amarok to fake all fsync and it fixed it but there are other apps that try to secure my data by syncing (I'm now running azareus and only fsyncs called every minute can explain writing to disk at full speed almost non stop while I'm downloading only 64KB/s ). So my question is: is there any way to disable fsync for reiser4? (beside patching it to fake fsync instead of doing them). Thanks for great fs. Łukasz Mierzwa
Re: any way to disable fsync?
On Tue, 2006-07-11 at 23:03 +0200, Łukasz Mierzwa wrote: [snip] So my question is: is there any way to disable fsync for reiser4? (beside patching it to fake fsync instead of doing them). http://ftp.die.net/pub/qmail-tools/libnosync.c -- Jonathan Briggs [EMAIL PROTECTED] eSoft, Inc. signature.asc Description: This is a digitally signed message part
Re: any way to disable fsync?
Łukasz Mierzwa wrote: Hi I got problem with apps that are calling fsync, it makes my hard drive flush like mad and it slows down things quite a lot. Example: I'm using amarok and amrok uses sqlite for storing data, sqlite calls fsync after every write so on song change amarok writes to sqlite some statistic data about what I listen and sqllite calls fsync, now I got amarok trying to load next song and sqlite fsyncing and the problem is that fsyncing under reiser4 is expensive, it takes a lot of time even if I'm only running amarok and nothing else ( I got 4200RPM drive in my notebook so it;s not a speed daemon). I patched sqlite in amarok to fake all fsync and it fixed it but there are other apps that try to secure my data by syncing (I'm now running azareus and only fsyncs called every minute can explain writing to disk at full speed almost non stop while I'm downloading only 64KB/s ). So my question is: is there any way to disable fsync for reiser4? (beside patching it to fake fsync instead of doing them). Thanks for great fs. Łukasz Mierzwa Just insert a return in the fsync code, it will be an amusing beginner kernel project for you. If you make it into a mount option we'll give you credit in the code for it. Alternatively, wait a few months, and fsync will be optimized.
Re: any way to disable fsync?
On Tue, 11 Jul 2006 23:03:12 +0200, =?iso-8859-2?B?o3VrYXN6IE1pZXJ6d2E=?= said: I got problem with apps that are calling fsync, it makes my hard drive flush like mad and it slows down things quite a lot. Several have posted how to bypass it. I'll pose the opposite side: Usually, applications call fsync() because they're pretty sure that if the disk and in-memory copies aren't lined up, a crash at that point could result in data loss and/or corruption. So sqlite calls fsync() - probably because if it *doesn't*, and your system crashes/reboots, you *will* lose that sqlite database. Your data, your decision. pgpTVO6hloYbk.pgp Description: PGP signature
Re: any way to disable fsync?
There are legitimate applications where the value of data is low enough and the load is high enough, that losing the database upon crash is ok. I have mixed feelings about making it a mount option for reiser4 because many users will not know what they do. In the end though, I should just sell the rope and advise but not control what people do with it. If someone writes it I will take a mount option patch to disable fsync iff it comes with documentation that has a lot of warnings.
Re: any way to disable fsync?
On Tue, 11 Jul 2006 17:04:56 PDT, Hans Reiser said: There are legitimate applications where the value of data is low enough and the load is high enough, that losing the database upon crash is ok. I have mixed feelings about making it a mount option for reiser4 because many users will not know what they do. In the end though, I should just sell the rope and advise but not control what people do with it. If someone writes it I will take a mount option patch to disable fsync iff it comes with documentation that has a lot of warnings. Two things to consider before writing code: 1) Should it be done at the VFS level instead of in the filesystem? Architecturally, it might be better there, so it applies to ext3 and jfs and others too... 2) Alternatively, should it be done on a per-file basis (possibly flagged with a chattr or similar)? It can't be done as an open() flag or ioctl(), because you're trying to override what the code does... That way, you can mitigate any fsync() load caused by one file, and still not leave yourself open to being screwed by some other application that tries to fsync() in other directories on that filesystem. It would be Really Bad if /home/fred/db23.sqlite gets corrupted because the filesystem was mounted -nofsync because of /home/george/moby.sqlite overhead pgpVCab4SeTph.pgp Description: PGP signature
Re: any way to disable fsync?
Dnia Wed, 12 Jul 2006 01:41:10 +0200, Toby Thain [EMAIL PROTECTED] napisał: On 11-Jul-06, at 5:57 PM, [EMAIL PROTECTED] wrote: On Tue, 11 Jul 2006 23:03:12 +0200, =?iso-8859-2?B? o3VrYXN6IE1pZXJ6d2E=?= said: I got problem with apps that are calling fsync, it makes my hard drive flush like mad and it slows down things quite a lot. Several have posted how to bypass it. I'll pose the opposite side: Usually, applications call fsync() because they're pretty sure that if the disk and in-memory copies aren't lined up, a crash at that point could result in data loss and/or corruption. So sqlite calls fsync() - probably because if it *doesn't*, and your system crashes/reboots, you *will* lose that sqlite database. Absolutely; it's required for commit semantics. :-) Your data, your decision. I know it's there to keep data integrity but what should I do when it makes some apps unusable? Becouse it really hurts amarok for me and without disabling it in sqlite code amarok I can't call it listening to music. I can always patch one or few apps and live with it but what if half of my apps will do it? Anyway I'm goint to work now so I won't be having this problem for next 8 hours.
Re: any way to disable fsync?
[EMAIL PROTECTED] wrote: On Tue, 11 Jul 2006 17:04:56 PDT, Hans Reiser said: There are legitimate applications where the value of data is low enough and the load is high enough, that losing the database upon crash is ok. I have mixed feelings about making it a mount option for reiser4 because many users will not know what they do. In the end though, I should just sell the rope and advise but not control what people do with it. If someone writes it I will take a mount option patch to disable fsync iff it comes with documentation that has a lot of warnings. Two things to consider before writing code: 1) Should it be done at the VFS level instead of in the filesystem? Architecturally, it might be better there, so it applies to ext3 and jfs and others too... Yes, if the below is not done. 2) Alternatively, should it be done on a per-file basis (possibly flagged with a chattr or similar)? Once the pseudofiles interface or sys_reiser4() are debugged and working, yes. It can't be done as an open() flag or ioctl(), because you're trying to override what the code does... That way, you can mitigate any fsync() load caused by one file, and still not leave yourself open to being screwed by some other application that tries to fsync() in other directories on that filesystem. It would be Really Bad if /home/fred/db23.sqlite gets corrupted because the filesystem was mounted -nofsync because of /home/george/moby.sqlite overhead
