From: Jesper Dangaard Brouer <brouer@redhat.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: daniel@iogearbox.net, ast@fb.com, bpf@vger.kernel.org,
netdev@vger.kernel.org, brouer@redhat.com,
Roman Gushchin <guro@fb.com>,
kernel-team@fb.com
Subject: Re: [PATCH bpf] samples/bpf: Set rlimit for memlock to infinity in all samples
Date: Tue, 27 Oct 2020 08:14:40 +0100 [thread overview]
Message-ID: <20201027081440.756cd175@carbon> (raw)
In-Reply-To: <20201026233623.91728-1-toke@redhat.com>
On Tue, 27 Oct 2020 00:36:23 +0100
Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> The memlock rlimit is a notorious source of failure for BPF programs. Most
> of the samples just set it to infinity, but a few used a lower limit. The
> problem with unconditionally setting a lower limit is that this will also
> override the limit if the system-wide setting is *higher* than the limit
> being set, which can lead to failures on systems that lock a lot of memory,
> but set 'ulimit -l' to unlimited before running a sample.
>
> One fix for this is to only conditionally set the limit if the current
> limit is lower, but it is simpler to just unify all the samples and have
> them all set the limit to infinity.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
This change basically disable the memlock rlimit system. And this
disable method is becoming standard in more and more BPF programs.
IMHO using the system-wide memlock rlimit doesn't make sense for BPF.
I'm still ACKing the patch, as this seems the only way forward, to
ignore and in-practice not use the memlock rlimit.
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
I saw some patches on the list (from Facebook) with a new system for
policy limiting memory usage per BPF program or was it mem-cgroup, but
I don't think that was ever merged... I would really like to see
something replace (and remove) this memlock rlimit dependency. Anyone
knows what happened to that effort?
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2020-10-27 7:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 23:36 [PATCH bpf] samples/bpf: Set rlimit for memlock to infinity in all samples Toke Høiland-Jørgensen
2020-10-27 3:52 ` Andrii Nakryiko
2020-10-27 7:14 ` Jesper Dangaard Brouer [this message]
2020-10-27 17:00 ` Roman Gushchin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201027081440.756cd175@carbon \
--to=brouer@redhat.com \
--cc=ast@fb.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=guro@fb.com \
--cc=kernel-team@fb.com \
--cc=netdev@vger.kernel.org \
--cc=toke@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).