[linus:master] [xfs] 9b64ca202f: fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec 24.1% regression

[linus:master] [xfs] 9b64ca202f: fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec 24.1% regression

[kernel test robot]

Hello,

kernel test robot noticed a 24.1% regression of fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec on:


commit: 9b64ca202f364a6bf8e19bdd20953bc2d776c67f ("xfs: store an agbno in struct xfs_imap")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

[still regression on linus/master      a635d6748234582ea287c5ffeae28b9b23f91c7e]
[still regression on linux-next/master bee763d5f341b99cf472afeb508d4988f62a6ca1]

testcase: fxmark
config: x86_64-rhel-9.4
compiler: gcc-14
test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory
parameters:

	disk: 1SSD
	media: ssd
	test: DRBH
	fstype: xfs
	directio: bufferedio
	thread_nr: 4
	cpufreq_governor: performance




If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202607161601.867c143e-lkp@intel.com


Details are as below:
-------------------------------------------------------------------------------------------------->


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260716/202607161601.867c143e-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/directio/disk/fstype/kconfig/media/rootfs/tbox_group/test/testcase/thread_nr:
  gcc-14/performance/bufferedio/1SSD/xfs/x86_64-rhel-9.4/ssd/debian-13-x86_64-20250902.cgz/lkp-icl-2sp8/DRBH/fxmark/4

commit: 
  caffb4252c ("xfs: massage xfs_imap_to_bp into xfs_read_icluster")
  9b64ca202f ("xfs: store an agbno in struct xfs_imap")

caffb4252cf15c5c 9b64ca202f364a6bf8e19bdd209 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
     23.90 ±  3%     -12.6%      20.88 ±  3%  fxmark.ssd_xfs_DRBH_4_bufferedio.user_sec
     12.24 ±  3%     -12.9%      10.67 ±  4%  fxmark.ssd_xfs_DRBH_4_bufferedio.user_util
 3.662e+08 ±  4%     -24.1%   2.78e+08 ±  4%  fxmark.ssd_xfs_DRBH_4_bufferedio.works
   7324905 ±  4%     -24.1%    5559335 ±  4%  fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec
     76773 ±  5%     +13.3%      87019 ± 10%  cpuidle..usage
     10.88 ±  3%     -12.1%       9.56 ±  6%  iostat.cpu.user
     11.27 ±  3%      -1.3        9.96 ±  6%  mpstat.cpu.all.usr%
      2332 ±  2%      +6.5%       2483 ±  6%  vmstat.system.cs
      1.34 ± 49%    +112.1%       2.85 ± 31%  perf-sched.sch_delay.avg.ms.perf_trace_sched_switch.preempt_schedule_irq.irqentry_exit.asm_sysvec_apic_timer_interrupt.current_time
      1.89 ± 46%    +763.1%      16.29 ± 43%  perf-sched.sch_delay.max.ms.perf_trace_sched_switch.preempt_schedule_irq.irqentry_exit.asm_sysvec_apic_timer_interrupt.current_time
     66.33 ± 17%     +69.8%     112.67 ± 28%  perf-sched.wait_and_delay.count.perf_trace_sched_switch.preempt_schedule_thunk.filemap_get_read_batch.filemap_get_pages.filemap_read
      1.34 ± 49%    +112.1%       2.85 ± 31%  perf-sched.wait_time.avg.ms.perf_trace_sched_switch.preempt_schedule_irq.irqentry_exit.asm_sysvec_apic_timer_interrupt.current_time
      1.89 ± 46%    +763.1%      16.29 ± 43%  perf-sched.wait_time.max.ms.perf_trace_sched_switch.preempt_schedule_irq.irqentry_exit.asm_sysvec_apic_timer_interrupt.current_time
      5.58 ±104%      -4.4        1.19 ±223%  perf-profile.calltrace.cycles-pp.pv_native_safe_halt.acpi_safe_halt.acpi_idle_do_entry.acpi_idle_enter.cpuidle_enter_state
      4.45 ±117%      -3.3        1.11 ±223%  perf-profile.calltrace.cycles-pp.lru_gen_del_folio.__page_cache_release.folios_put_refs.free_pages_and_swap_cache.__tlb_batch_free_encoded_pages
      3.26 ±101%      -3.3        0.00        perf-profile.calltrace.cycles-pp.__page_cache_release.folios_put_refs.free_pages_and_swap_cache.__tlb_batch_free_encoded_pages.tlb_flush_mmu
      4.30 ± 72%      -2.8        1.52 ±223%  perf-profile.calltrace.cycles-pp.mutex_unlock.sw_perf_event_destroy.__free_event.perf_event_release_kernel.perf_release
      4.15 ± 74%      -2.3        1.87 ±145%  perf-profile.calltrace.cycles-pp.tear_down_vmas.exit_mmap.__mmput.exit_mm.do_exit
      4.14 ±103%      -1.6        2.58 ±160%  perf-profile.calltrace.cycles-pp.__dentry_kill.finish_dput.__fput.task_work_run.do_exit
      4.14 ±103%      -1.6        2.58 ±160%  perf-profile.calltrace.cycles-pp.finish_dput.__fput.task_work_run.do_exit.do_group_exit
      3.11 ±101%      -1.1        2.04 ±148%  perf-profile.calltrace.cycles-pp.free_unref_folios.folios_put_refs.free_pages_and_swap_cache.__tlb_batch_free_encoded_pages.tlb_finish_mmu
      3.26 ±101%      -0.7        2.58 ±160%  perf-profile.calltrace.cycles-pp.kmem_cache_free.__dentry_kill.finish_dput.__fput.task_work_run
      4.45 ±117%      -3.3        1.11 ±223%  perf-profile.children.cycles-pp.lru_gen_del_folio
      4.45 ±117%      -2.6        1.84 ±146%  perf-profile.children.cycles-pp.__page_cache_release
      4.15 ± 74%      -2.3        1.87 ±145%  perf-profile.children.cycles-pp.tear_down_vmas
      4.30 ± 72%      -1.5        2.80 ±142%  perf-profile.children.cycles-pp.mutex_unlock
      4.30 ± 72%      -1.5        2.80 ±142%  perf-profile.self.cycles-pp.mutex_unlock




Disclaimer:
Results have been estimated based on internal Intel analysis and are provided
for informational purposes only. Any difference in system hardware or software
design or configuration may affect actual performance.


-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [linus:master] [xfs] 9b64ca202f: fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec 24.1% regression

[Christoph Hellwig]

On Thu, Jul 16, 2026 at 09:13:19PM +0800, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed a 24.1% regression of fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec on:
> 

This looks really odd.  While the patch adds a bit more computation,
that is very cheap shifting and masking.  So the only theory I have here
is that this somehow affects the inode data layout.  Can you re-run this
with the patch below applied on top of commit
9b64ca202f364a6bf8e19bdd20953bc2d776c67f ?

diff --git a/fs/xfs/libxfs/xfs_inode_buf.h b/fs/xfs/libxfs/xfs_inode_buf.h
index 57192adc7744..319e83d4a087 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.h
+++ b/fs/xfs/libxfs/xfs_inode_buf.h
@@ -15,6 +15,7 @@ struct xfs_dinode;
  */
 struct xfs_imap {
 	xfs_agblock_t	im_agbno;	/* starting agbno of inode cluster */
+	uint32_t	__im_pad;
 	unsigned short	im_boffset;	/* offset in inode cluster in bytes */
 };