On Tue, Sep 30, 2014 at 12:48:45PM +0200, Jan Kara wrote:
> On Tue 30-09-14 10:11:32, Thanos Makatos wrote:
> >
> > Regarding extending the ioctl to invalidate the page cache, do you have
> > any suggestions where I could start looking?
> You just need to call invalidate_inode_pages2(). That is going to do all
> you need.
>
> > Would such a new ioctl have any chance to be accepted upstream?
> I believe a possibility for a file to be fully flushed from page cache is
> useful at times and if you present well your usecase there are reasonable
> chances it will get accepted upstream.
Agreed, this seems reasonable. How many times have we all dropped our
entire cache just 'cause we didn't have a more precise tool?
$ grep -ri drop_caches xfstests/
xfstests/src/fsync-tester.c: if ((fd = open("/proc/sys/vm/drop_caches", O_WRONLY)) < 0) {
xfstests/src/stale_handle.c: system("echo 3 > /proc/sys/vm/drop_caches");
xfstests/common/quota: echo 3 > /proc/sys/vm/drop_caches
The last one even says:
# XXX: really need an ioctl instead of this big hammer
echo 3 > /proc/sys/vm/drop_caches
:)
- z
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