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e298c8a818
After traversing all directory entries, hint the empty directory
entry no matter whether or not there are enough empty directory
entries.
After this commit, hint the empty directory entries like this:
1. Hint the deleted directory entries if enough;
2. Hint the deleted and unused directory entries which at the
end of the cluster chain no matter whether enough or not(Add
by this commit);
3. If no any empty directory entries, hint the empty directory
entries in the new cluster(Add by this commit).
This avoids repeated traversal of directory entries, reduces CPU
usage, and improves the performance of creating files and
directories(especially on low-performance CPUs).
Test create 5000 files in a class 4 SD card on imx6q-sabrelite
with:
for ((i=0;i<5;i++)); do
sync
time (for ((j=1;j<=1000;j++)); do touch file$((i*1000+j)); done)
done
The more files, the more performance improvements.
Before After Improvement
1~1000 25.360s 22.168s 14.40%
1001~2000 38.242s 28.72ss 33.15%
2001~3000 49.134s 35.037s 40.23%
3001~4000 62.042s 41.624s 49.05%
4001~5000 73.629s 46.772s 57.42%
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Andy Wu <Andy.Wu@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.