On Fri, 27 Jun 2014, Matthias Schniedermeyer wrote: > Date: Fri, 27 Jun 2014 10:41:39 +0200 > From: Matthias Schniedermeyer <m...@citd.de> > To: Luká? Czerner <lczer...@redhat.com> > Cc: Artem Bityutskiy <dedeki...@gmail.com>, > Bernd Schubert <bernd.schub...@itwm.fraunhofer.de>, > Dave Chinner <da...@fromorbit.com>, Thomas Knauth <thomas.kna...@gmx.de>, > David Rientjes <rient...@google.com>, > Maksym Planeta <mcsim.plan...@gmail.com>, > Alexander Viro <v...@zeniv.linux.org.uk>, linux-fsde...@vger.kernel.org, > linux-kernel@vger.kernel.org > Subject: Re: [PATCH] sysctl: Add a feature to drop caches selectively > > On 26.06.2014 13:57, Luká? Czerner wrote: > > > > So if the authors want to sell this new interface (in whatever form) to > > > the kernel community, they should start with providing a solid use-case, > > > with some more details, explore alternatives and show how the > > > alternatives do not work for them. > > > > Yes please, let's see some solid use-case for this. > > Personally i would want it to verify files after copying them: > Especially while moving files: > - Copy a file > - <drop cache> > - Verify that it really is correct on stable storage > - Remove original file
I assume you're using cp to copy a file, not your own program. In that case can we make cp optionally use direct io ? It seems that it would solve your problem in very elegant way. -Lukas > > Currently i choose either of the 3 ways: > - drop_caches > - umount/mount > - Write more data than memory in machine (Which is only an > approximnation and you have to verify in the same order the files were > written, so it is likely that any cache was thrashed in the meantime) > > But having a way to selectivly "destory" the cache of a file would make > this task easier. > > > > >
