All of lore.kernel.org
 help / color / mirror / Atom feed
From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>, Jens Axboe <axboe@kernel.dk>,
	Keith Busch <kbusch@kernel.org>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH blk-next 1/2] blk-mq-rdma: Delete not-used multi-queue RDMA map queue code
Date: Tue, 6 Oct 2020 07:58:00 +0300	[thread overview]
Message-ID: <20201006045800.GE1874917@unreal> (raw)
In-Reply-To: <20201005083817.GA14908@lst.de>

On Mon, Oct 05, 2020 at 10:38:17AM +0200, Christoph Hellwig wrote:
> On Fri, Oct 02, 2020 at 01:20:35PM -0700, Sagi Grimberg wrote:
> >> Well, why would they change it?  The whole point of the infrastructure
> >> is that there is a single sane affinity setting for a given setup. Now
> >> that setting needed some refinement from the original series (e.g. the
> >> current series about only using housekeeping cpus if cpu isolation is
> >> in use).  But allowing random users to modify affinity is just a receipe
> >> for a trainwreck.
> >
> > Well allowing people to mangle irq affinity settings seem to be a hard
> > requirement from the discussions in the past.
> >
> >> So I think we need to bring this back ASAP, as doing affinity right
> >> out of the box is an absolute requirement for sane performance without
> >> all the benchmarketing deep magic.
> >
> > Well, it's hard to say that setting custom irq affinity settings is
> > deemed non-useful to anyone and hence should be prevented. I'd expect
> > that irq settings have a sane default that works and if someone wants to
> > change it, it can but there should be no guarantees on optimal
> > performance. But IIRC this had some dependencies on drivers and some
> > more infrastructure to handle dynamic changes...
>
> The problem is that people change random settings.  We need to generalize
> it into a sane API (e.g. the housekeeping CPUs thing which totally makes
> sense).

I don't see many people jump on the bandwagon, someone should do it, but
who will? I personally have no knowledge in that area to do anything
meaningful.

Thanks

WARNING: multiple messages have this Message-ID (diff)
From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Sagi Grimberg <sagi@grimberg.me>,
	linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>, Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH blk-next 1/2] blk-mq-rdma: Delete not-used multi-queue RDMA map queue code
Date: Tue, 6 Oct 2020 07:58:00 +0300	[thread overview]
Message-ID: <20201006045800.GE1874917@unreal> (raw)
In-Reply-To: <20201005083817.GA14908@lst.de>

On Mon, Oct 05, 2020 at 10:38:17AM +0200, Christoph Hellwig wrote:
> On Fri, Oct 02, 2020 at 01:20:35PM -0700, Sagi Grimberg wrote:
> >> Well, why would they change it?  The whole point of the infrastructure
> >> is that there is a single sane affinity setting for a given setup. Now
> >> that setting needed some refinement from the original series (e.g. the
> >> current series about only using housekeeping cpus if cpu isolation is
> >> in use).  But allowing random users to modify affinity is just a receipe
> >> for a trainwreck.
> >
> > Well allowing people to mangle irq affinity settings seem to be a hard
> > requirement from the discussions in the past.
> >
> >> So I think we need to bring this back ASAP, as doing affinity right
> >> out of the box is an absolute requirement for sane performance without
> >> all the benchmarketing deep magic.
> >
> > Well, it's hard to say that setting custom irq affinity settings is
> > deemed non-useful to anyone and hence should be prevented. I'd expect
> > that irq settings have a sane default that works and if someone wants to
> > change it, it can but there should be no guarantees on optimal
> > performance. But IIRC this had some dependencies on drivers and some
> > more infrastructure to handle dynamic changes...
>
> The problem is that people change random settings.  We need to generalize
> it into a sane API (e.g. the housekeeping CPUs thing which totally makes
> sense).

I don't see many people jump on the bandwagon, someone should do it, but
who will? I personally have no knowledge in that area to do anything
meaningful.

Thanks

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2020-10-06  4:58 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-29  9:13 [PATCH blk-next 0/2] Delete the get_vector_affinity leftovers Leon Romanovsky
2020-09-29  9:13 ` Leon Romanovsky
2020-09-29  9:13 ` [PATCH blk-next 1/2] blk-mq-rdma: Delete not-used multi-queue RDMA map queue code Leon Romanovsky
2020-09-29  9:13   ` Leon Romanovsky
2020-09-29 10:20   ` Christoph Hellwig
2020-09-29 10:20     ` Christoph Hellwig
2020-09-29 10:35     ` Leon Romanovsky
2020-09-29 10:35       ` Leon Romanovsky
2020-09-29 18:24       ` Sagi Grimberg
2020-09-29 18:24         ` Sagi Grimberg
2020-10-02  6:45         ` Christoph Hellwig
2020-10-02  6:45           ` Christoph Hellwig
2020-10-02 20:20           ` Sagi Grimberg
2020-10-02 20:20             ` Sagi Grimberg
2020-10-05  8:38             ` Christoph Hellwig
2020-10-05  8:38               ` Christoph Hellwig
2020-10-06  4:58               ` Leon Romanovsky [this message]
2020-10-06  4:58                 ` Leon Romanovsky
2020-09-29  9:13 ` [PATCH blk-next 2/2] RDMA/core: Delete not-implemented get_vector_affinity Leon Romanovsky
2020-09-29  9:13   ` Leon Romanovsky
2020-10-01  5:01 ` [PATCH blk-next 0/2] Delete the get_vector_affinity leftovers Leon Romanovsky
2020-10-01  5:01   ` Leon Romanovsky
2020-10-02  1:28   ` Jens Axboe
2020-10-02  1:28     ` Jens Axboe

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=20201006045800.GE1874917@unreal \
    --to=leon@kernel.org \
    --cc=axboe@kernel.dk \
    --cc=dledford@redhat.com \
    --cc=hch@lst.de \
    --cc=jgg@nvidia.com \
    --cc=kbusch@kernel.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvme@lists.infradead.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=sagi@grimberg.me \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.