From: Wang Yugui <wangyugui@e16-tech.com>
To: linux-btrfs@vger.kernel.org
Subject: question about the performance of 'btrfs send'
Date: Sat, 15 Oct 2022 20:35:01 +0800 [thread overview]
Message-ID: <20221015203501.E1ED.409509F4@e16-tech.com> (raw)
Hi,
a question about the performance of 'btrfs send'.
The output speed of 'btrfs send' is about 700MiB/s in the 3 cases.
1) kernel 5.15.73 + 'btrfs send --proto 1'
2) kernel: 6.0.1(with btrfs-devel misc-6.1) + 'btrfs send --proto 1'
3) kernel: 6.0.1(with btrfs-devel misc-6.1) + 'btrfs send --proto 2'
btrfs-progs: 6.0
the outut of 'perf report':
Overhead Command Shared Object Symbol
*1 40.63% btrfs [kernel.kallsyms] [k] __crc32c_le
*2 9.97% btrfs [kernel.kallsyms] [k] memcpy_erms
*3 9.25% btrfs [kernel.kallsyms] [k] send_extent_data
*4 5.40% btrfs [kernel.kallsyms] [k] asm_exc_nmi
*5 2.73% btrfs [kernel.kallsyms] [k] __alloc_pages
1.14% btrfs [kernel.kallsyms] [k] __rmqueue_pcplist
0.92% btrfs [kernel.kallsyms] [k] bad_range
0.88% btrfs [kernel.kallsyms] [k] get_page_from_freelist
What I expected:
the above *1) __crc32c_le take >60%, and the outut speed > 1GiB/s.
The *1) __crc32c_le is necessary operation, and the speed
seems OK. 2GB/s * 40% = 800MiB/s, it is close to 700MiB/s.
Question:
The above *3) is difficult to understand. Any advice?
Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2022/10/15
next reply other threads:[~2022-10-15 12:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-15 12:35 Wang Yugui [this message]
2022-10-17 13:02 ` question about the performance of 'btrfs send' David Sterba
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