[vbox-dev] [PATCH] Performance improvement of vboxsf by using page cache

[Tatsuya Karino]

Here is another patch for the improvement of vboxsf.

The key point is using page cache in the system call read/write.
I created this patch by reference to the other file system(e.g. ext4, nfs,
vmhgfs).

In this patch...
* To use page cache, generic_file_read_iter/generic_file_write_iter will be
called from read/write.
* the page cache will be cleared in sf_inode_revalidate if necessary.
* sf_inode_revalidate will be called in a cache sensitive function like
read_iter, write_iter.
* sf_inode_revalidate will not call unnecessary stat.

I tested this code on a kernel 3.19 Linux guest.
This patch is provided under the MIT license.


# before apply this patch
vagrant at debian-jessie:/vagrant$ for i in {0..2}; do time cat
large-file>/dev/null ; done

real  0m0.045s
user  0m0.000s
sys 0m0.020s

real  0m0.031s
user  0m0.000s
sys 0m0.016s

real  0m0.045s
user  0m0.000s
sys 0m0.020s


# after apply this patch
vagrant at debian-jessie:/vagrant$ for i in {0..2}; do time cat
large-file>/dev/null ; done

real  0m0.140s
user  0m0.000s
sys 0m0.072s

real  0m0.004s
user  0m0.000s
sys 0m0.000s

real  0m0.004s
user  0m0.000s
sys 0m0.000s

Thanks,

-- 
Tatsuya Karino
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