On Thu, Nov 04, 2021 at 02:47:03AM +0800, Jimmy Shiu wrote: > trace_sched_blocked_trace in CFS is really useful for debugging via > trace because it tell where the process was stuck on callstack. > > For example, > <...>-6143 ( 6136) [005] d..2 50.278987: sched_blocked_reason: pid=6136 iowait=0 caller=SyS_mprotect+0x88/0x208 > <...>-6136 ( 6136) [005] d..2 50.278990: sched_blocked_reason: pid=6142 iowait=0 caller=do_page_fault+0x1f4/0x3b0 > <...>-6142 ( 6136) [006] d..2 50.278996: sched_blocked_reason: pid=6144 iowait=0 caller=SyS_prctl+0x52c/0xb58 > <...>-6144 ( 6136) [006] d..2 50.279007: sched_blocked_reason: pid=6136 iowait=0 caller=vm_mmap_pgoff+0x74/0x104 > > However, sometime it gives pointless information like this. > RenderThread-2322 ( 1805) [006] d.s3 50.319046: sched_blocked_reason: pid=6136 iowait=1 caller=__lock_page_killable+0x17c/0x220 > logd.writer-594 ( 587) [002] d.s3 50.334011: sched_blocked_reason: pid=6126 iowait=1 caller=wait_on_page_bit+0x194/0x208 > kworker/u16:13-333 ( 333) [007] d.s4 50.343161: sched_blocked_reason: pid=6136 iowait=1 caller=__lock_page_killable+0x17c/0x220 > /me peers at coffee Maybe I'm blind but aside from Matthew's concerns, this appears to rely on an Android patch that is not upstream https://android.googlesource.com/kernel/msm/+/c9f00aa0e25e397533c198a0fcf6246715f99a7b%5E!/ -- Mel Gorman SUSE Labs
