[PATCH v2] erofs: add a global page pool for lz4 decompression

[Chunhai Guo]

On 2024/1/9 21:08, Gao Xiang wrote:
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>
> Hi Chunhai,
>
> On 2024/1/9 15:41, Chunhai Guo wrote:
>> Using a global page pool for LZ4 decompression significantly reduces the
>> time spent on page allocation in low memory scenarios.
>>
>> The table below shows the reduction in time spent on page allocation for
>> LZ4 decompression when using a global page pool.  The results were
>> obtained from multi-app launch benchmarks on ARM64 Android devices
>> running the 5.15 kernel with an 8-core CPU and 8GB of memory.  In the
>> benchmark, we launched 16 frequently-used apps, and the camera app was
>> the last one in each round. The data in the table is the average time of
>> camera app for each round.
>> After using the page pool, there was an average improvement of 150ms in
>> the launch time of the camera app, which was obtained from systrace log.
>> +--------------+---------------+--------------+---------+
>> |              | w/o page pool | w/ page pool |  diff   |
>> +--------------+---------------+--------------+---------+
>> | Average (ms) |     3434      |      21      | -99.38% |
>> +--------------+---------------+--------------+---------+
>>
>> Based on the benchmark logs, 64 pages are sufficient for 95% of
>> scenarios. This value can be adjusted from the module parameter. The
>> default value is 0.
>>
>> This patch currently only supports the LZ4 decompressor, other
>> decompressors will be supported in the next step.
>>
>> Signed-off-by: Chunhai Guo <guochunhai at vivo.com>
>
> This patch looks good to me, yet we're in the merge window for v6.8.
> I will address it after -rc1 is out since no stable tag these days.
>
> Also it would be better to add some results of changing max_distance
> if you have more time to test.

OK. I will reply to this email when the experiment is finished.

Thanks.

>
> Thanks,
> Gao Xiang