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libbpf: switch libbpf_num_possible_cpus() implementation to simpler sysconf(_SC_NPROCESSORS_CONF) call #383

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anakryiko opened this issue Sep 17, 2021 · 6 comments
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libbpf: switch libbpf_num_possible_cpus() implementation to simpler sysconf(_SC_NPROCESSORS_CONF) call #383

anakryiko opened this issue Sep 17, 2021 · 6 comments
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good first issue Good for newcomers improvement Improvements to existing functionality
Milestone
libbpf-1.0

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@anakryiko
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There is no need to parse files. We need to double-check, but there is probably also no way that sysconf() can fail, which makes the API use simpler.
@anakryiko anakryiko added good first issue Good for newcomers improvement Improvements to existing functionality labels Sep 17, 2021
@anakryiko anakryiko added this to the libbpf-1.0 milestone Sep 17, 2021
@mfrw
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mfrw commented Sep 21, 2021

@anakryiko Can I take a stab at it ?

@anakryiko
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Sure! Just keep in mind that libbpf changes have to go through kernel tree (bpf-next in this case), so please submit the patch to bpf@vger.kernel.org. See https://kernelnewbies.org/FirstKernelPatch and https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html if it will be your first kernel patch submission.

@mfrw
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mfrw commented Sep 21, 2021 •
edited

One point, since sysconf sets the errno we probably can avoid using libbpf_err.
Is my understanding correct ?

Something like this.

@anakryiko
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Let's not split discussion into two parts. Replied on mailing list.

kernel-patches-bot pushed a commit to kernel-patches/bpf that referenced this issue Sep 22, 2021
@mfrw
libbpf: Use sysconf to simplify libbpf_num_possible_cpus
1eca012 
Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF)
instead of parsing a file.
This patch is a part ([0]) of libbpf-1.0 milestone.

[0] Closes: libbpf/libbpf#383

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
tsipa pushed a commit to tsipa/bpf-next that referenced this issue Sep 22, 2021
@mfrw
libbpf: Use sysconf to simplify libbpf_num_possible_cpus
e2a9131 
Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF)
instead of parsing a file.
This patch is a part ([0]) of libbpf-1.0 milestone.

[0] Closes: libbpf/libbpf#383

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
fengguang pushed a commit to 0day-ci/linux that referenced this issue Sep 22, 2021
@mfrw @intel-lab-lkp
libbpf: Use sysconf to simplify libbpf_num_possible_cpus
671b7eb 
Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF)
instead of parsing a file.
This patch is a part ([0]) of libbpf-1.0 milestone.

[0] Closes: libbpf/libbpf#383

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
tsipa pushed a commit to tsipa/bpf-next that referenced this issue Sep 22, 2021
@mfrw
libbpf: Use sysconf to simplify libbpf_num_possible_cpus
3d91b4d 
Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF)
instead of parsing a file.
This patch is a part ([0]) of libbpf-1.0 milestone.

[0] Closes: libbpf/libbpf#383

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
kernel-patches-bot pushed a commit to kernel-patches/bpf that referenced this issue Sep 22, 2021
@mfrw
libbpf: Use sysconf to simplify libbpf_num_possible_cpus
1720d54 
Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF)
instead of parsing a file.
This patch is a part ([0]) of libbpf-1.0 milestone.

[0] Closes: libbpf/libbpf#383

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
@mfrw
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mfrw commented Sep 25, 2021

@anakryiko Should we probably close this issue ?

@anakryiko
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We are not going to do that. https://lore.kernel.org/bpf/ef0f23d0-456a-70b0-1ef9-2615a5528278@iogearbox.net/ for explanation of why not.

@wgblikeW wgblikeW mentioned this issue Jul 22, 2022
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