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Dave Chinner ec08c14ba2 xfs: type verification is expensive
From a concurrent rm -rf workload:

  41.04%  [kernel]  [k] xfs_dir3_leaf_check_int
   9.85%  [kernel]  [k] __xfs_dir3_data_check
   5.60%  [kernel]  [k] xfs_verify_ino
   5.32%  [kernel]  [k] xfs_agino_range
   4.21%  [kernel]  [k] memcpy
   3.06%  [kernel]  [k] xfs_errortag_test
   2.57%  [kernel]  [k] xfs_dir_ino_validate
   1.66%  [kernel]  [k] xfs_dir2_data_get_ftype
   1.17%  [kernel]  [k] do_raw_spin_lock
   1.11%  [kernel]  [k] xfs_verify_dir_ino
   0.84%  [kernel]  [k] __raw_callee_save___pv_queued_spin_unlock
   0.83%  [kernel]  [k] xfs_buf_find
   0.64%  [kernel]  [k] xfs_log_commit_cil

THere's an awful lot of overhead in just range checking inode
numbers in that, but each inode number check is not a lot of code.
The total is a bit over 14.5% of the CPU time is spent validating
inode numbers.

The problem is that they deeply nested global scope functions so the
overhead here is all in function call marshalling.

   text	   data	    bss	    dec	    hex	filename
   2077	      0	      0	   2077	    81d fs/xfs/libxfs/xfs_types.o.orig
   2197	      0	      0	   2197	    895	fs/xfs/libxfs/xfs_types.o

There's a small increase in binary size by inlining all the local
nested calls in the verifier functions, but the same workload now
profiles as:

  40.69%  [kernel]  [k] xfs_dir3_leaf_check_int
  10.52%  [kernel]  [k] __xfs_dir3_data_check
   6.68%  [kernel]  [k] xfs_verify_dir_ino
   4.22%  [kernel]  [k] xfs_errortag_test
   4.15%  [kernel]  [k] memcpy
   3.53%  [kernel]  [k] xfs_dir_ino_validate
   1.87%  [kernel]  [k] xfs_dir2_data_get_ftype
   1.37%  [kernel]  [k] do_raw_spin_lock
   0.98%  [kernel]  [k] xfs_buf_find
   0.94%  [kernel]  [k] __raw_callee_save___pv_queued_spin_unlock
   0.73%  [kernel]  [k] xfs_log_commit_cil

Now we only spend just over 10% of the time validing inode numbers
for the same workload. Hence a few "inline" keyworks is good enough
to reduce the validation overhead by 30%...

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-03-25 16:47:51 -07:00
arch Boundary condition fixes for bugs unearthed by the perf fuzzer. 2021-03-21 11:26:21 -07:00
block block: Discard page cache of zone reset target range 2021-03-11 11:49:25 -07:00
certs certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID 2021-01-21 16:16:10 +00:00
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
Documentation xfs: rename the blockgc workqueue 2021-03-25 16:47:50 -07:00
drivers Staging/IIO driver fixes for 5.12-rc4 2021-03-21 11:54:04 -07:00
fs xfs: type verification is expensive 2021-03-25 16:47:51 -07:00
include USB / Thunderbolt driver fixes for 5.12-rc4 2021-03-21 11:49:16 -07:00
init Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel io_uring-5.12-2021-03-21 2021-03-21 12:25:54 -07:00
lib kasan: fix KASAN_STACK dependency for HW_TAGS 2021-03-13 11:27:31 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
net module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
samples Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
scripts kbuild: fix ld-version.sh to not be affected by locale 2021-03-13 11:12:13 +09:00
security Revert 95ebabde38 ("capabilities: Don't allow writing ambiguous v3 file capabilities") 2021-03-12 15:27:14 -06:00
sound sound fixes for 5.12-rc4 2021-03-19 09:53:32 -07:00
tools selftests: kvm: add set_boot_cpu_id test 2021-03-18 13:55:14 -04:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore clang-lto series for v5.12-rc1 2021-02-23 09:28:51 -08:00
.mailmap treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: move the staging subsystem to lists.linux.dev 2021-03-16 12:17:26 +01:00
Makefile Linux 5.12-rc4 2021-03-21 14:56:43 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.