All of lore.kernel.org
 help / color / mirror / Atom feed
From: Rusty Russell <rusty@rustcorp.com.au>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, brouer@redhat.com, minipli@googlemail.com
Subject: Re: [PATCH] pktgen: nowait parameter.
Date: Thu, 11 Sep 2014 09:07:29 +0930	[thread overview]
Message-ID: <871trjjbd2.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20140905.142618.2240630803375505977.davem@davemloft.net>

David Miller <davem@davemloft.net> writes:
> From: Rusty Russell <rusty@rustcorp.com.au>
> Date: Wed, 03 Sep 2014 13:50:01 +0930
>
>> While trying to measure speed of virtio_net, I was getting hangs.
>> This is because we skb_orphan() but delay the tx interrupt
>> indefinitely (by number of slots).
>> 
>> With nowait, pktgen won't wait for the skb to be released.  This
>> introduces an error, but it's ok if count >> ringsize.
>> 
>> I updated the documentation, but it needs far more work (it
>> refers to pgset and an examples directory, none of which exist
>> in the kernel tree).
>> 
>> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
>
> Please just make this a flag, like UDPCSUM, NO_TIMESTAMP, et al.
> Which also means that it should be capitalized.

Agreed, though I prefer Jason's IFF_TX_SKB_FREE_DELAY, which doesn't
require intimate knowledge of the driver to get the option correct.

> BTW, wrt. holding onto TX frames for unbounded amounts of time, I
> think this is a bad idea even with skb_orphan().  There are resources
> from the SKB you are hanging onto which can stall the removal of
> modules indefinitely, such as netfilter references.

We could certainly have a once-a-second timer which did this, but should
skb_orphan() do that work instead?

Cheers,
Rusty.

  reply	other threads:[~2014-09-10 23:46 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-03  4:20 [PATCH] pktgen: nowait parameter Rusty Russell
2014-09-03  9:09 ` Jesper Dangaard Brouer
2014-09-05  1:49   ` Rusty Russell
2014-09-05  2:52     ` Jason Wang
2014-09-05 21:26 ` David Miller
2014-09-10 23:37   ` Rusty Russell [this message]
2014-09-12 21:52     ` David Miller

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=871trjjbd2.fsf@rustcorp.com.au \
    --to=rusty@rustcorp.com.au \
    --cc=brouer@redhat.com \
    --cc=davem@davemloft.net \
    --cc=minipli@googlemail.com \
    --cc=netdev@vger.kernel.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 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.