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SubjectRe: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression
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Christoph Hellwig <hch@lst.de> writes:

> Snipping the long contest:
>
> I think there are three observations here:
>
> (1) removing the mark_page_accessed (which is the only significant
> change in the parent commit) hurts the
> aim7/1BRD_48G-xfs-disk_rr-3000-performance/ivb44 test.
> I'd still rather stick to the filemap version and let the
> VM people sort it out. How do the numbers for this test
> look for XFS vs say ext4 and btrfs?
> (2) lots of additional spinlock contention in the new case. A quick
> check shows that I fat-fingered my rewrite so that we do
> the xfs_inode_set_eofblocks_tag call now for the pure lookup
> case, and pretty much all new cycles come from that.
> (3) Boy, are those xfs_inode_set_eofblocks_tag calls expensive, and
> we're already doing way to many even without my little bug above.
>
> So I've force pushed a new version of the iomap-fixes branch with
> (2) fixed, and also a little patch to xfs_inode_set_eofblocks_tag a
> lot less expensive slotted in before that. Would be good to see
> the numbers with that.

For the original reported regression, the test result is as follow,

=========================================================================================
compiler/cpufreq_governor/debug-setup/disk/fs/kconfig/load/rootfs/tbox_group/test/testcase:
gcc-6/performance/profile/1BRD_48G/xfs/x86_64-rhel/3000/debian-x86_64-2015-02-07.cgz/ivb44/disk_wrt/aim7

commit:
f0c6bcba74ac51cb77aadb33ad35cb2dc1ad1506 (parent of first bad commit)
68a9f5e7007c1afa2cf6830b690a90d0187c0684 (first bad commit)
99091700659f4df965e138b38b4fa26a29b7eade (base of your fixes branch)
bf4dc6e4ecc2a3d042029319bc8cd4204c185610 (head of your fixes branch)

f0c6bcba74ac51cb 68a9f5e7007c1afa2cf6830b69 99091700659f4df965e138b38b bf4dc6e4ecc2a3d042029319bc
---------------- -------------------------- -------------------------- --------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
484435 ± 0% -13.3% 420004 ± 0% -17.0% 402250 ± 0% -15.6% 408998 ± 0% aim7.jobs-per-min


And the perf data is as follow,

"perf-profile.func.cycles-pp.intel_idle": 20.25,
"perf-profile.func.cycles-pp.memset_erms": 11.72,
"perf-profile.func.cycles-pp.copy_user_enhanced_fast_string": 8.37,
"perf-profile.func.cycles-pp.__block_commit_write.isra.21": 3.49,
"perf-profile.func.cycles-pp.block_write_end": 1.77,
"perf-profile.func.cycles-pp.native_queued_spin_lock_slowpath": 1.63,
"perf-profile.func.cycles-pp.unlock_page": 1.58,
"perf-profile.func.cycles-pp.___might_sleep": 1.56,
"perf-profile.func.cycles-pp.__block_write_begin_int": 1.33,
"perf-profile.func.cycles-pp.iov_iter_copy_from_user_atomic": 1.23,
"perf-profile.func.cycles-pp.up_write": 1.21,
"perf-profile.func.cycles-pp.__mark_inode_dirty": 1.18,
"perf-profile.func.cycles-pp.down_write": 1.06,
"perf-profile.func.cycles-pp.mark_buffer_dirty": 0.94,
"perf-profile.func.cycles-pp.generic_write_end": 0.92,
"perf-profile.func.cycles-pp.__radix_tree_lookup": 0.91,
"perf-profile.func.cycles-pp._raw_spin_lock": 0.81,
"perf-profile.func.cycles-pp.entry_SYSCALL_64_fastpath": 0.79,
"perf-profile.func.cycles-pp.__might_sleep": 0.79,
"perf-profile.func.cycles-pp.xfs_file_iomap_begin_delay.isra.9": 0.7,
"perf-profile.func.cycles-pp.__list_del_entry": 0.7,
"perf-profile.func.cycles-pp.vfs_write": 0.69,
"perf-profile.func.cycles-pp.drop_buffers": 0.68,
"perf-profile.func.cycles-pp.xfs_file_write_iter": 0.67,
"perf-profile.func.cycles-pp.rwsem_spin_on_owner": 0.67,

Best Regards,
Huang, Ying

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