* [linux-next:master] [btrfs] 9a8eec6165: fio.write_iops 22.6% regression
@ 2026-03-11 14:36 kernel test robot
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From: kernel test robot @ 2026-03-11 14:36 UTC (permalink / raw)
To: Leo Martins
Cc: oe-lkp, lkp, David Sterba, Filipe Manana, Sun YangKai,
Boris Burkov, linux-btrfs, oliver.sang
Hello,
kernel test robot noticed a 22.6% regression of fio.write_iops on:
commit: 9a8eec6165a01f1aa97619c96cc5dbad86ddbb62 ("btrfs: inhibit extent buffer writeback to prevent COW amplification")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
[still regression on linux-next/master a0ae2a256046c0c5d3778d1a194ff2e171f16e5f]
testcase: fio-basic
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:
runtime: 300s
disk: 1HDD
fs: btrfs
nr_task: 1
test_size: 128G
rw: randwrite
bs: 4k
ioengine: ftruncate
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/202603112240.f7605968-lkp@intel.com
Details are as below:
-------------------------------------------------------------------------------------------------->
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260311/202603112240.f7605968-lkp@intel.com
=========================================================================================
bs/compiler/cpufreq_governor/disk/fs/ioengine/kconfig/nr_task/rootfs/runtime/rw/tbox_group/test_size/testcase:
4k/gcc-14/performance/1HDD/btrfs/ftruncate/x86_64-rhel-9.4/1/debian-13-x86_64-20250902.cgz/300s/randwrite/lkp-icl-2sp9/128G/fio-basic
commit:
444cfd8d1f ("btrfs: skip COW for written extent buffers allocated in current transaction")
9a8eec6165 ("btrfs: inhibit extent buffer writeback to prevent COW amplification")
444cfd8d1f160c14 9a8eec6165a01f1aa97619c96cc
---------------- ---------------------------
%stddev %change %stddev
\ | \
0.07 ± 31% +0.5 0.57 ± 10% fio.latency_10us%
0.01 ± 44% +0.0 0.03 ± 6% fio.latency_250us%
99.84 -50.0 49.80 fio.latency_2us%
0.10 ± 24% +49.5 49.59 fio.latency_4us%
58.98 +29.0% 76.08 fio.time.elapsed_time
58.98 +29.0% 76.08 fio.time.elapsed_time.max
428.33 ± 8% +2798.9% 12417 ± 9% fio.time.involuntary_context_switches
101.17 -2.8% 98.33 fio.time.percent_of_cpu_this_job_got
46.62 +31.7% 61.42 fio.time.system_time
6277 +28.8% 8084 fio.time.voluntary_context_switches
2236 -22.6% 1731 fio.write_bw_MBps
1576 +42.5% 2245 fio.write_clat_90%_ns
1592 +44.1% 2293 fio.write_clat_95%_ns
1632 +53.9% 2512 ± 2% fio.write_clat_99%_ns
1495 +33.4% 1995 fio.write_clat_mean_ns
284.48 ± 37% +1017.7% 3179 ± 5% fio.write_clat_stddev
572669 -22.6% 443293 fio.write_iops
3.806e+09 +28.4% 4.886e+09 cpuidle..time
133227 +62.5% 216453 ± 4% cpuidle..usage
107.81 +15.9% 124.96 uptime.boot
6550 +16.5% 7632 uptime.idle
1887 +13.7% 2146 vmstat.system.cs
4426 ± 2% +8.9% 4822 ± 3% vmstat.system.in
0.06 ± 6% -0.0 0.05 ± 11% mpstat.cpu.all.iowait%
0.00 ± 13% +0.0 0.02 ± 15% mpstat.cpu.all.soft%
0.97 -0.2 0.77 mpstat.cpu.all.usr%
94.50 -8.3% 86.67 turbostat.Avg_MHz
2.64 -0.2 2.42 turbostat.Busy%
1.51 +6.5% 1.61 turbostat.IPC
232693 +43.5% 333974 ± 2% turbostat.IRQ
2.00 ± 55% +3334.3% 68.76 ± 10% perf-sched.total_wait_and_delay.average.ms
815.67 ± 8% +389.2% 3990 ± 9% perf-sched.total_wait_and_delay.count.ms
52.14 ± 12% +4876.0% 2594 ± 14% perf-sched.total_wait_and_delay.max.ms
1.92 ± 57% +3464.7% 68.59 ± 10% perf-sched.total_wait_time.average.ms
37.19 ± 31% +6613.9% 2496 ± 17% perf-sched.total_wait_time.max.ms
2.00 ± 55% +3334.3% 68.76 ± 10% perf-sched.wait_and_delay.avg.ms.[unknown].[unknown].[unknown].[unknown].[unknown]
815.67 ± 8% +389.2% 3990 ± 9% perf-sched.wait_and_delay.count.[unknown].[unknown].[unknown].[unknown].[unknown]
52.14 ± 12% +4876.0% 2594 ± 14% perf-sched.wait_and_delay.max.ms.[unknown].[unknown].[unknown].[unknown].[unknown]
1.92 ± 57% +3464.7% 68.59 ± 10% perf-sched.wait_time.avg.ms.[unknown].[unknown].[unknown].[unknown].[unknown]
37.19 ± 31% +6613.9% 2496 ± 17% perf-sched.wait_time.max.ms.[unknown].[unknown].[unknown].[unknown].[unknown]
1.33 -0.2 1.10 perf-stat.i.branch-miss-rate%
33302690 -16.2% 27896465 ± 2% perf-stat.i.branch-misses
8.43 ± 12% -5.8 2.61 ± 6% perf-stat.i.cache-miss-rate%
6149698 +171.1% 16672847 perf-stat.i.cache-references
1682 +16.8% 1965 ± 2% perf-stat.i.context-switches
0.64 -6.4% 0.60 perf-stat.i.cpi
6.157e+09 -8.5% 5.634e+09 perf-stat.i.cpu-cycles
71.04 +8.4% 77.01 ± 4% perf-stat.i.cpu-migrations
9.288e+09 -2.6% 9.045e+09 perf-stat.i.instructions
1.69 +5.8% 1.79 perf-stat.i.ipc
1.68 -0.3 1.41 perf-stat.overall.branch-miss-rate%
9.36 ± 4% -6.2 3.20 ± 5% perf-stat.overall.cache-miss-rate%
0.66 -6.0% 0.62 perf-stat.overall.cpi
1.51 +6.4% 1.60 perf-stat.overall.ipc
16487 +25.0% 20616 perf-stat.overall.path-length
32749408 -15.9% 27542708 ± 2% perf-stat.ps.branch-misses
6059888 +171.7% 16467123 perf-stat.ps.cache-references
1655 +17.2% 1940 ± 2% perf-stat.ps.context-switches
6.061e+09 -8.2% 5.567e+09 perf-stat.ps.cpu-cycles
69.88 +8.8% 76.02 ± 4% perf-stat.ps.cpu-migrations
9.135e+09 -2.3% 8.93e+09 perf-stat.ps.instructions
5.532e+11 +25.0% 6.918e+11 perf-stat.total.instructions
9.27 ± 32% -9.3 0.00 perf-profile.calltrace.cycles-pp.proc_reg_read_iter.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
9.27 ± 32% -9.3 0.00 perf-profile.calltrace.cycles-pp.seq_read_iter.proc_reg_read_iter.vfs_read.ksys_read.do_syscall_64
8.21 ± 32% -7.5 0.76 ±223% perf-profile.calltrace.cycles-pp.folio_remove_rmap_ptes.zap_present_ptes.zap_pte_range.zap_pmd_range.unmap_page_range
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.acpi_idle_do_entry.acpi_idle_enter.cpuidle_enter_state.cpuidle_enter.cpuidle_idle_call
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.acpi_idle_enter.cpuidle_enter_state.cpuidle_enter.cpuidle_idle_call.do_idle
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.acpi_safe_halt.acpi_idle_do_entry.acpi_idle_enter.cpuidle_enter_state.cpuidle_enter
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.common_startup_64
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.cpu_startup_entry.start_secondary.common_startup_64
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.cpuidle_enter.cpuidle_idle_call.do_idle.cpu_startup_entry.start_secondary
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.cpuidle_enter_state.cpuidle_enter.cpuidle_idle_call.do_idle.cpu_startup_entry
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.cpuidle_idle_call.do_idle.cpu_startup_entry.start_secondary.common_startup_64
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.do_idle.cpu_startup_entry.start_secondary.common_startup_64
5.50 ± 83% -5.5 0.00 perf-profile.calltrace.cycles-pp.start_secondary.common_startup_64
5.44 ± 45% -5.4 0.00 perf-profile.calltrace.cycles-pp.arch_show_interrupts.seq_read_iter.proc_reg_read_iter.vfs_read.ksys_read
4.39 ±112% -4.4 0.00 perf-profile.calltrace.cycles-pp.pv_native_safe_halt.acpi_safe_halt.acpi_idle_do_entry.acpi_idle_enter.cpuidle_enter_state
5.99 ± 50% -4.3 1.74 ±143% perf-profile.calltrace.cycles-pp.__tlb_batch_free_encoded_pages.tlb_flush_mmu.zap_pte_range.zap_pmd_range.unmap_page_range
5.99 ± 50% -4.3 1.74 ±143% perf-profile.calltrace.cycles-pp.folios_put_refs.free_pages_and_swap_cache.__tlb_batch_free_encoded_pages.tlb_flush_mmu.zap_pte_range
5.99 ± 50% -4.3 1.74 ±143% perf-profile.calltrace.cycles-pp.free_pages_and_swap_cache.__tlb_batch_free_encoded_pages.tlb_flush_mmu.zap_pte_range.zap_pmd_range
5.99 ± 50% -4.3 1.74 ±143% perf-profile.calltrace.cycles-pp.tlb_flush_mmu.zap_pte_range.zap_pmd_range.unmap_page_range.unmap_vmas
3.84 ±104% -3.8 0.00 perf-profile.calltrace.cycles-pp.show_interrupts.seq_read_iter.proc_reg_read_iter.vfs_read.ksys_read
3.82 ±104% -3.8 0.00 perf-profile.calltrace.cycles-pp.__open64_nocancel
3.82 ±104% -3.8 0.00 perf-profile.calltrace.cycles-pp.__x64_sys_openat.do_syscall_64.entry_SYSCALL_64_after_hwframe.__open64_nocancel
3.82 ±104% -3.8 0.00 perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.__open64_nocancel
3.82 ±104% -3.8 0.00 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.__open64_nocancel
5.49 ±129% -3.8 1.68 ±142% perf-profile.calltrace.cycles-pp.do_sys_openat2.__x64_sys_openat.do_syscall_64.entry_SYSCALL_64_after_hwframe.__open64_nocancel
4.93 ± 75% -2.4 2.56 ±145% perf-profile.calltrace.cycles-pp.do_anonymous_page.__handle_mm_fault.handle_mm_fault.do_user_addr_fault.exc_page_fault
3.82 ±104% -2.3 1.52 ±223% perf-profile.calltrace.cycles-pp.alloc_anon_folio.do_anonymous_page.__handle_mm_fault.handle_mm_fault.do_user_addr_fault
3.28 ±100% -2.3 0.98 ±223% perf-profile.calltrace.cycles-pp.dup_mm.copy_process.kernel_clone.__do_sys_clone.do_syscall_64
3.28 ±100% -2.3 0.98 ±223% perf-profile.calltrace.cycles-pp.dup_mmap.dup_mm.copy_process.kernel_clone.__do_sys_clone
9.27 ± 32% -9.3 0.00 perf-profile.children.cycles-pp.proc_reg_read_iter
8.21 ± 32% -7.5 0.76 ±223% perf-profile.children.cycles-pp.folio_remove_rmap_ptes
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.acpi_idle_do_entry
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.acpi_idle_enter
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.acpi_safe_halt
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.common_startup_64
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.cpu_startup_entry
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.cpuidle_enter
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.cpuidle_enter_state
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.cpuidle_idle_call
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.do_idle
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.pv_native_safe_halt
5.50 ± 83% -5.5 0.00 perf-profile.children.cycles-pp.start_secondary
5.44 ± 45% -5.4 0.00 perf-profile.children.cycles-pp.arch_show_interrupts
5.99 ± 50% -4.3 1.74 ±143% perf-profile.children.cycles-pp.tlb_flush_mmu
3.84 ±104% -3.8 0.00 perf-profile.children.cycles-pp.show_interrupts
5.49 ±129% -3.8 1.68 ±142% perf-profile.children.cycles-pp.__open64_nocancel
4.93 ± 75% -2.4 2.56 ±145% perf-profile.children.cycles-pp.do_anonymous_page
3.82 ±104% -2.3 1.52 ±223% perf-profile.children.cycles-pp.alloc_anon_folio
3.28 ±100% -2.3 0.98 ±223% perf-profile.children.cycles-pp.dup_mm
3.28 ±100% -2.3 0.98 ±223% perf-profile.children.cycles-pp.dup_mmap
5.91 ± 50% -5.9 0.00 perf-profile.self.cycles-pp.folio_remove_rmap_ptes
4.24 ± 70% -4.2 0.00 perf-profile.self.cycles-pp.arch_show_interrupts
3.20 ±100% -3.2 0.00 perf-profile.self.cycles-pp.pv_native_safe_halt
3.89 ±103% -3.0 0.88 ±223% perf-profile.self.cycles-pp.kmem_cache_free
4.95 ± 75% -2.9 2.02 ±141% perf-profile.self.cycles-pp.__d_lookup
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
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2026-03-11 14:36 [linux-next:master] [btrfs] 9a8eec6165: fio.write_iops 22.6% regression kernel test robot
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