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fix runqlen.py with 4.15 kernel #1510

Merged
merged 1 commit into from
Jan 4, 2018
Merged

fix runqlen.py with 4.15 kernel #1510

merged 1 commit into from
Jan 4, 2018

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yonghong-song
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The following kernel commit changes linux_src:kernel/sched/sched.h
struct cfs_rq structure:

commit 1ea6c46a23f1213d1972bfae220db5c165e27bba
Author: Peter Zijlstra <[email protected]>
Date:   Sat May 6 15:59:54 2017 +0200

    sched/fair: Propagate an effective runnable_load_avg

    The load balancer uses runnable_load_avg as load indicator. For
    !cgroup this is:

      runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

    That is, a direct sum of all runnable tasks on that runqueue. As
    opposed to load_avg, which is a sum of all tasks on the runqueue,
    which includes a blocked component.
...

The commit is in kernel 4.15 release and will make current
runqlen.py internal cfs_rq_partial structure not syncing with the kernel one.
As a result, runqlen.py will produce incorrect results on 4.15.

This patch attempts to solve this issue by compiling a bpf program,
which accesses one of fields introduced by the above commit.
The successful compilation will indicate that we should amend
the cfs_rq_partial structure.

Signed-off-by: Yonghong Song [email protected]

@yonghong-song
fix runqlen.py with 4.15 kernel
ffa47e6 
The following kernel commit changes linux_src:kernel/sched/sched.h
struct cfs_rq structure:

```
commit 1ea6c46a23f1213d1972bfae220db5c165e27bba
Author: Peter Zijlstra <[email protected]>
Date:   Sat May 6 15:59:54 2017 +0200

    sched/fair: Propagate an effective runnable_load_avg

    The load balancer uses runnable_load_avg as load indicator. For
    !cgroup this is:

      runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

    That is, a direct sum of all runnable tasks on that runqueue. As
    opposed to load_avg, which is a sum of all tasks on the runqueue,
    which includes a blocked component.
...
```

The commit is in kernel 4.15 release and will make current
runqlen.py internal cfs_rq_partial structure not syncing with the kernel one.
As a result, runqlen.py will produce incorrect results on 4.15.

This patch attempts to solve this issue by compiling a bpf program,
which accesses one of fields introduced by the above commit.
The successful compilation will indicate that we should amend
the cfs_rq_partial structure.

Signed-off-by: Yonghong Song <[email protected]>
@yonghong-song
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cc @brendangregg

@4ast 4ast merged commit 484e525 into master Jan 4, 2018
@brendangregg
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Thanks @yonghong-song , I like the code comment!

@ismhong ismhong mentioned this pull request May 2, 2023
Closed
ismhong pushed a commit to ismhong/bcc that referenced this pull request May 8, 2023
runqlen/cpuunclaimed: Fix runnable_weight issue after Linux 5.7
46d140e 
runqlen / cpuunclaimed add check_runnable_weight_field() as workaround to
check runnable_weight presents in struct cfs_rq in kernel/sched/sched.h by
trying to access runnable_weight field of struct
sched_entity in include/linux/sched.h. Please check more details in PR iovisor#1510
and iovisor#2164.

Unfortunately, the runnable_weight field of struct cfs_rq is removed, but the
runnable_weight field of struct sched_entity is remained by following patchset
series from Linux version 5.7.0.

- https://yhbt.net/lore/all/[email protected]/
- https://yhbt.net/lore/all/[email protected]/

Please also check the source of Linux below.

- include/linux/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/include/linux/sched.h#L475
- kernel/sched/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/kernel/sched/sched.h#L502

This PR checks runnable_weight field exists by using kernel_struct_has_field()
if target system with BTF enabled, otherwise fallback to legacy on-the-fly
compiling check. In the meantime, add Linux version 5.7.0 check in
structure definition cfs_rq_partial to prevent issue if target system
w/o BTF enabled and Linux version > 5.7.

Please check more details in iovisor#4602.

Signed-off-by: Ism Hong <[email protected]>
@ismhong ismhong mentioned this pull request May 8, 2023
Merged
ismhong pushed a commit to ismhong/bcc that referenced this pull request May 8, 2023
runqlen/cpuunclaimed: Fix runnable_weight issue after Linux 5.7
dcfcb98 
runqlen / cpuunclaimed add check_runnable_weight_field() as workaround to
check runnable_weight presents in struct cfs_rq in kernel/sched/sched.h by
trying to access runnable_weight field of struct
sched_entity in include/linux/sched.h. Please check more details in PR iovisor#1510
and iovisor#2164.

Unfortunately, the runnable_weight field of struct cfs_rq is removed, but the
runnable_weight field of struct sched_entity is remained by following patchset
series from Linux version 5.7.0.

- https://yhbt.net/lore/all/[email protected]/
- https://yhbt.net/lore/all/[email protected]/

Please also check the source of Linux below.

- include/linux/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/include/linux/sched.h#L475
- kernel/sched/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/kernel/sched/sched.h#L502

This PR checks runnable_weight field exists by using kernel_struct_has_field()
if target system with BTF enabled, otherwise fallback to legacy on-the-fly
compiling check. In the meantime, add Linux version 5.7.0 check in
structure definition cfs_rq_partial to prevent issue if target system
w/o BTF enabled and Linux version > 5.7.

Please check more details in iovisor#4602.

Signed-off-by: Ism Hong <[email protected]>
ismhong pushed a commit to ismhong/bcc that referenced this pull request May 16, 2023
runqlen/cpuunclaimed: Fix runnable_weight issue after Linux 5.7
e33d0ae 
runqlen / cpuunclaimed add check_runnable_weight_field() as workaround to
check runnable_weight presents in struct cfs_rq in kernel/sched/sched.h by
trying to access runnable_weight field of struct
sched_entity in include/linux/sched.h. Please check more details in PR iovisor#1510
and iovisor#2164.

Unfortunately, the runnable_weight field of struct cfs_rq is removed, but the
runnable_weight field of struct sched_entity is remained by following patchset
series from Linux version 5.7.0.

- https://yhbt.net/lore/all/[email protected]/
- https://yhbt.net/lore/all/[email protected]/

Please also check the source of Linux below.

- include/linux/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/include/linux/sched.h#L475
- kernel/sched/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/kernel/sched/sched.h#L502

This PR checks runnable_weight field exists by using kernel_struct_has_field()
if target system with BTF enabled, otherwise fallback to legacy on-the-fly
compiling check. In the meantime, add Linux version 5.7.0 check in
structure definition cfs_rq_partial to prevent issue if target system
w/o BTF enabled and Linux version > 5.7.

Please check more details in iovisor#4602.

Signed-off-by: Ism Hong <[email protected]>
yonghong-song pushed a commit that referenced this pull request May 19, 2023
@yonghong-song
runqlen/cpuunclaimed: Fix runnable_weight issue after Linux 5.7
46a125d 
runqlen / cpuunclaimed add check_runnable_weight_field() as workaround to
check runnable_weight presents in struct cfs_rq in kernel/sched/sched.h by
trying to access runnable_weight field of struct
sched_entity in include/linux/sched.h. Please check more details in PR #1510
and #2164.

Unfortunately, the runnable_weight field of struct cfs_rq is removed, but the
runnable_weight field of struct sched_entity is remained by following patchset
series from Linux version 5.7.0.

- https://yhbt.net/lore/all/[email protected]/
- https://yhbt.net/lore/all/[email protected]/

Please also check the source of Linux below.

- include/linux/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/include/linux/sched.h#L475
- kernel/sched/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/kernel/sched/sched.h#L502

This PR checks runnable_weight field exists by using kernel_struct_has_field()
if target system with BTF enabled, otherwise fallback to legacy on-the-fly
compiling check. In the meantime, add Linux version 5.7.0 check in
structure definition cfs_rq_partial to prevent issue if target system
w/o BTF enabled and Linux version > 5.7.

Please check more details in #4602.

Signed-off-by: Ism Hong <[email protected]>
captain5050 pushed a commit to captain5050/bcc that referenced this pull request Oct 12, 2023
@captain5050
runqlen/cpuunclaimed: Fix runnable_weight issue after Linux 5.7
8a20e35 
runqlen / cpuunclaimed add check_runnable_weight_field() as workaround to
check runnable_weight presents in struct cfs_rq in kernel/sched/sched.h by
trying to access runnable_weight field of struct
sched_entity in include/linux/sched.h. Please check more details in PR iovisor#1510
and iovisor#2164.

Unfortunately, the runnable_weight field of struct cfs_rq is removed, but the
runnable_weight field of struct sched_entity is remained by following patchset
series from Linux version 5.7.0.

- https://yhbt.net/lore/all/[email protected]/
- https://yhbt.net/lore/all/[email protected]/

Please also check the source of Linux below.

- include/linux/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/include/linux/sched.h#L475
- kernel/sched/sched.h
    - https://elixir.bootlin.com/linux/v5.7/source/kernel/sched/sched.h#L502

This PR checks runnable_weight field exists by using kernel_struct_has_field()
if target system with BTF enabled, otherwise fallback to legacy on-the-fly
compiling check. In the meantime, add Linux version 5.7.0 check in
structure definition cfs_rq_partial to prevent issue if target system
w/o BTF enabled and Linux version > 5.7.

Please check more details in iovisor#4602.

Signed-off-by: Ism Hong <[email protected]>
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@brendangregg brendangregg Awaiting requested review from brendangregg brendangregg is a code owner

@goldshtn goldshtn Awaiting requested review from goldshtn goldshtn is a code owner

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@yonghong-song @brendangregg @4ast