On Sun, Oct 20, 2013 at 11:19:26PM +0800, lilofile wrote: > > when i read transaction_kthread function in disk-io.c > > delay = HZ * 30; > > why commit transaction is 30 seconds, Other values 20 seconds,10 seconds? > what considerations about the commit transaction interval? It's a more or less arbitrary number. There's been a patch recently (last couple of months) to allow modifying the value. If you make it too large, you end up using lots of RAM for unflushed changes, you risk losing those changes if the machine crashes. If you make it too small, you end up writing lots more metadata, because that's always changing as the FS is modified. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- There are three things you should never see being made: laws, --- standards, and sausages.
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