Messages in this thread | | | Subject | Re: drive/block device write scheduling, buffer flushing? | Date | Thu, 1 Feb 2001 09:56:12 +0100 (MET) | From | (Rogier Wolff) |
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bert hubert wrote: > On Wed, Jan 31, 2001 at 11:52:25AM -0500, Nathan Black wrote: > > I was wondering if there is a way to make the kernel write to disk faster. > > I need to maintain a 10 MB /sec write rate to a 10K scsi disk in a computer, > > but it caches and doesn't start writing to disk until I hit about 700 MB. At > > that point, it pauses(presumably while the kernel is flushing some of the > > buffers) and I will have missed data that I am trying to capture. > > try opening with O_SYNC, or call fsync() every once in a while. Otherwise, > this sounds like an application for a raw device, whereby you can write > directly to the disk, with no caching in between.
But you'll probably need to use "buffer" too.
capture | buffer -m 128m > outputfile
Otherwise the "fsync" can block you for say 1/10th of a second, causing loss of a few frames. (10MB per seconds sure sounds like video).
Roger.
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * There are old pilots, and there are bold pilots. * There are also old, bald pilots. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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