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270700dd06
Most compressors are actually CPU-based and won't sleep during compression and decompression. We should remove the redundant memcpy for them. This patch checks if the algorithm is sleepable by testing the CRYPTO_ALG_ASYNC algorithm flag. Generally speaking, async and sleepable are semantically similar but not equal. But for compress drivers, they are basically equal at least due to the below facts. Firstly, scompress drivers - crypto/deflate.c, lz4.c, zstd.c, lzo.c etc have no sleep. Secondly, zRAM has been using these scompress drivers for years in atomic contexts, and never worried those drivers going to sleep. One exception is that an async driver can sometimes still return synchronously per Herbert's clarification. In this case, we are still having a redundant memcpy. But we can't know if one particular acomp request will sleep or not unless crypto can expose more details for each specific request from offload drivers. Link: https://lkml.kernel.org/r/20240222081135.173040-3-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Tested-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: Nhat Pham <nphamcs@gmail.com> Acked-by: Yosry Ahmed <yosryahmed@google.com> Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com> Acked-by: Chris Li <chrisl@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: David S. Miller <davem@davemloft.net> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Seth Jennings <sjenning@redhat.com> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| certs | ||
| crypto | ||
| Documentation | ||
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| include | ||
| init | ||
| io_uring | ||
| ipc | ||
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| .clang-format | ||
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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.