在 2020/11/6 2:21, Eric Biggers 写道: > On Thu, Nov 05, 2020 at 05:05:53PM +0800, Li Qiang wrote: >> >> >> 在 2020/11/5 15:51, Ard Biesheuvel 写道: >>> Note that NEON intrinsics can be compiled for 32-bit ARM as well (with >>> a bit of care - please refer to lib/raid6/recov_neon_inner.c for an >>> example of how to deal with intrinsics that are only available on >>> arm64) and are less error prone, so intrinsics should be preferred if >>> feasible. >>> >>> However, you have still not explained how optimizing Adler32 makes a >>> difference for a real-world use case. Where is libdeflate used on a >>> hot path? >>> . >> >> Sorry :(, I have not specifically searched for the use of this algorithm >> in the kernel. >> >> When I used perf to test the performance of the libz library before, >> I saw that the adler32 algorithm occupies a lot of hot spots.I just >> saw this algorithm used in the kernel code, so I think optimizing this >> algorithm may have some positive optimization effects on the kernel.:) > > Adler32 performance is important for zlib compression/decompression, which has a > few use cases in the kernel such as btrfs compression. However, these days > those few kernel use cases are mostly switching to newer algorithms like lz4 and > zstd. Also as I mentioned, your patch doesn't actually wire up your code to be > used by the kernel's implementation of zlib compression/decompression. > > I think you'd be much better off contributing to a userspace project, where > DEFLATE/zlib/gzip support still has a long tail of use cases. The official zlib > isn't really being maintained and isn't accepting architecture-specific > optimizations, but there are some performance-oriented forks of zlib (e.g. > https://chromium.googlesource.com/chromium/src/third_party/zlib/ and > https://github.com/zlib-ng/zlib-ng), as well as other projects like libdeflate > (https://github.com/ebiggers/libdeflate). Generally I'm happy to accept > architecture-specific optimizations in libdeflate, but they need to be testable. > > - Eric > . > Thank you for your answers and suggestions. I have not seen these repositories before. Regarding the SVE implementation of adler32, I will focus on the repositories you mentioned later.:) -- Best regards, Li Qiang
