Messages in this thread |  | | | Date | Mon, 18 Aug 2003 23:20:24 -0700 | | From | Andrew Morton <> | | Subject | Re: cache limit |
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Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua> wrote: > > There was a discussion (and patches) in the middle of 2.5 series > about O_STREAMING open flag which mean "do not aggressively cache > this file". Targeted at MP3/video playing, copying large files and such. > > I don't know whether it actually was merged. If it was, > your program can use it.
It was not. Instead we have fadvise. So it would be appropriate to change applications such as rsync to optionally run
posix_fadvise(fd, 0, -1, POSIX_FADV_DONTNEED)
against file descriptors just before closing them, so all the pagecache gets thrown away. (Well, most of the pagecache - dirty pages won't get dropped - the app must fsync the files by hand first if it wants this)
This would be a useful addition to rsync and such applications - it is stronger and more specific and safer than banging on the VM for a special case.
But if you want to bang on the VM for a special case, run 2.6 and set /proc/sys/vm/swappiness to zero during the rsync run.
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