Regression Tracker
Introduction
Fastpath monitors the Linux kernel across a range of hardware platforms and workloads. When a statistically significant performance change is detected between two kernel versions, it is raised as a tracked regression entry and investigated. This page records all known findings together with their current status and, where available, links to upstream reports and fix commits.
Column descriptions:
ID – Tracking identifier (e.g.
FP-619-02).Branch / Good / Bad – The kernel tree and the two versions that bracket the regression.
SUT(s) – System(s) Under Test on which the regression was observed.
Benchmark / Resultclass – The specific workload and measured quantity.
Delta – Measured change between the good and bad kernel versions.
Date Detected – Date the regression was first bisected with a confirmed result (YYYY-MM-DD).
Regressing Commit – The first bad commit identified by bisection.
Status – One of five states:
Detected – Regression observed; queued for investigation.
Investigating – Currently under active investigation.
Reported – Reported upstream; awaiting a fix.
Resolving – Fix being discussed, developed, or verified upstream.
Fixed – Fix merged upstream.
Report – Link to the upstream mailing-list report or patch.
Date Fixed – Date the commit that fixes the regression was merged upstream (YYYY-MM-DD).
Fix Commit(s) – Commit(s) that resolved the regression.
Regression History
ID |
Branch |
Good Kernel |
Bad Kernel |
SUT(s) |
Benchmark / Resultclass |
Delta |
Date Detected |
Regressing Commit |
Status |
Report |
Date Fixed |
Fix Commit(s) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
FP-614-01 |
mainline |
6-13-0 |
6-14-0-rc4 |
aws-m7g.metal-01 |
mmtests/hackbench (process-pipes-30) |
-10.69% |
2025-03-05 |
“pipe_read: don’t wake up the writer if the pipe is still full” |
Fixed |
2025-03-04 |
“fs/pipe: Read pipe->{head,tail} atomically outside pipe->mutex” |
|
FP-615-01 |
mainline |
6-15-0-rc1 |
6-15-0-rc2 |
aws-m7g.metal-01 |
pts/pgbench Scale: 100 Clients: 1000, Read Only (TPS) |
-98.81% |
2025-05-12 |
“ACPI PPTT: Fix coding mistakes in a couple of sizeof() calls” |
Fixed |
2025-05-08 |
“ACPI: PPTT: Fix processor subtable walk” |
|
FP-619-01 |
mainline |
6-18-0 |
6-19-0-rc1 |
aws-m7g.metal-01 |
micromm/vmalloc fix_align_alloc_test: p:1, h:0, l:500000 (usec) |
-40.57% |
2025-12-10 |
“mm/vmalloc: request large order pages from buddy allocator” |
Resolving |
|||
FP-619-02 |
mainline |
6-18-0 |
6-19-0-rc1 |
|
schbench/thread-contention (-m 64 -t 4 -r 10 -s 1000), avg_rps (req/sec) |
-17.41% |
2025-12-12 |
“sched/fair: Reimplement NEXT_BUDDY to align with EEVDF goals” |
Fixed |
2026-01-23 |
|
|
FP-619-03 |
mainline |
6-18-0 |
6-19-0-rc2 |
aws-m7g.metal-01 |
micromm/munmap p:1, d:10 (seconds) |
-23.74% |
2026-01-23 |
“memcg: use mod_node_page_state to update stats” |
Reported |
|||
FP-700-01 |
mainline |
6-19-0 |
7-0-0-rc1 |
|
micromm/vmalloc kvfree_rcu_2_arg_vmalloc_test: p:1, h:0, l:500000 (usec) |
-9.26% |
2026-02-20 |
“slab: add sheaves to most caches” |
Resolving |
|
||
FP-700-02 |
mainline |
6-19-0 |
7-0-0-rc1 |
|
|
-7.60% |
2026-03-10 |
|
Resolving |
|