DPDK patches and discussions
 help / color / mirror / Atom feed
From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: David Marchand <david.marchand@redhat.com>
Cc: dev@dpdk.org, Olivier Matz <olivier.matz@6wind.com>,
	Kevin Traynor <ktraynor@redhat.com>,
	dpdk stable <stable@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] eal: restrict ctrl threads to startup cpu affinity
Date: Thu, 14 Feb 2019 10:04:59 +0000	[thread overview]
Message-ID: <4304821e-dd76-da80-2dec-e1c540e95ea5@intel.com> (raw)
In-Reply-To: <CAJFAV8zyeA16eY+mgq3_V2szUOV38=i0G_2uMjRDrUm-+fJq_w@mail.gmail.com>

On 14-Feb-19 9:53 AM, David Marchand wrote:
> On Thu, Feb 14, 2019 at 10:39 AM Burakov, Anatoly 
> <anatoly.burakov@intel.com <mailto:anatoly.burakov@intel.com>> wrote:
> 
>     On 13-Feb-19 4:13 PM, David Marchand wrote:
>      > Spawning the ctrl threads on anything that is not part of the eal
>      > coremask is not that polite to the rest of the system.
>      >
>      > Rather than introduce yet another eal options for this, let's take
>      > the startup cpu affinity as a reference and remove the eal coremask
>      > from it.
>      > If no cpu is left, then we default to the master core.
>      >
>      > The cpuset is computed once at init before the original cpu affinity.
>      >
>      > Fixes: d651ee4919cd ("eal: set affinity for control threads")
>      > Signed-off-by: David Marchand <david.marchand@redhat.com
>     <mailto:david.marchand@redhat.com>>
>      > ---
> 
>     Hi David,
> 
>     Maybe i didn't have enough coffee today and i'm missing something here,
>     but how is this different? Removing the coremask cores from the cpuset
>     will effectively "spawn the ctrl threads on anything that is not
>     part of
>     the EAL coremask" (which is "not that polite to the rest of the
>     system"), unless the application was run with taskset.
> 
>     Is "taskset" the key point here? I.e. by default, we're still "not
>     polite", unless the user asks nicely? :)
> 
> 
> Eheh, sorry, yes.
> A bit more context then, if you want to clearly pin cpu resources for 
> the processes on your system (let's say having virtual machines and a 
> popular vswitch), I can only think of two solutions.
> Either you have something to configure your processes to have them call 
> sched_setaffinity/pthread_set_affinity_np, or you use taskset to get 
> them "jailed" without them caring.
> 
> Before the incriminated commit, we were keeping all threads on the 
> coremask that had been passed, but as Olivier said, we would end up with 
> ctrl threads spanwed on core running dataplane threads as well.
> 
> Now, the ctrl threads can be spawned anywhere on all & ~coremask, with 
> no way to configure this.
> I considered adding a new eal option, but I think relying on the current 
> cpu affinity is a better default behavior and I can't see drawbacks at 
> the moment.
> 
> 
> -- 
> David Marchand
> 

OK, that makes sense. However, i feel this behavior (both old and new, 
for that matter) should be better documented somewhere in the EAL docs.

-- 
Thanks,
Anatoly

  reply	other threads:[~2019-02-14 10:05 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-13 16:13 David Marchand
2019-02-13 20:21 ` David Marchand
2019-02-14  9:39 ` Burakov, Anatoly
2019-02-14  9:53   ` David Marchand
2019-02-14 10:04     ` Burakov, Anatoly [this message]
2019-02-14 10:16       ` David Marchand
2019-02-14 11:05 ` David Marchand
2019-02-14 13:30 ` [dpdk-dev] [PATCH v2 1/2] eal: fix potential incorrect pinning for ctrl threads David Marchand
2019-02-14 13:30   ` [dpdk-dev] [PATCH v2 2/2] eal: restrict ctrl threads to startup cpu affinity David Marchand
2019-02-19 11:38     ` Burakov, Anatoly
2019-02-19 11:51       ` David Marchand
2019-02-19 16:03         ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2019-02-14 16:12   ` [dpdk-dev] [PATCH v2 1/2] eal: fix potential incorrect pinning for ctrl threads Burakov, Anatoly
2019-02-14 17:45     ` David Marchand
2019-02-19 20:41   ` [dpdk-dev] [PATCH v3 " David Marchand
2019-02-19 20:41     ` [dpdk-dev] [PATCH v3 2/2] eal: restrict ctrl threads to startup cpu affinity David Marchand
2019-02-20 16:01       ` Burakov, Anatoly
2019-02-25  8:33         ` Olivier Matz
2019-03-07 18:23           ` Thomas Monjalon
2019-02-20 16:01     ` [dpdk-dev] [PATCH v3 1/2] eal: fix potential incorrect pinning for ctrl threads Burakov, Anatoly
2019-02-25  8:33       ` Olivier Matz

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=4304821e-dd76-da80-2dec-e1c540e95ea5@intel.com \
    --to=anatoly.burakov@intel.com \
    --cc=david.marchand@redhat.com \
    --cc=dev@dpdk.org \
    --cc=ktraynor@redhat.com \
    --cc=olivier.matz@6wind.com \
    --cc=stable@dpdk.org \
    /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).