From: Bill Fink <billfink@mindspring.com>
To: "Ilpo Järvinen " <ilpo.jarvinen@helsinki.fi>
Cc: David Miller <davem@davemloft.net>,
Herbert Xu <herbert@gondor.apana.org.au>,
Netdev <netdev@vger.kernel.org>, John Heffner <jheffner@psc.edu>
Subject: Re: TSO trimming question
Date: Fri, 21 Dec 2007 14:37:07 -0500 [thread overview]
Message-ID: <20071221143707.fbb0ae60.billfink@mindspring.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0712212056220.31652@kivilampi-30.cs.helsinki.fi>
On Fri, 21 Dec 2007, Ilpo Järvinen wrote:
> On Fri, 21 Dec 2007, Bill Fink wrote:
>
> > On Fri, 21 Dec 2007, Bill Fink wrote:
> >
> > > Or perhaps even:
> > >
> > > /* Ok, it looks like it is advisable to defer. */
> > > tp->tso_deferred = jiffies;
> > >
> > > /* need to return a non-zero value to defer, which means won't
> > > * defer if jiffies == 0 but it's only a 1 in 4 billion event
> > > * (and avoids a compare/branch by not checking jiffies)
> > > /
> > > return jiffies;
> >
> > Ack. I introduced my own 64-bit to 32-bit issue (too late at night).
> > How about:
> >
> > /* Ok, it looks like it is advisable to defer. */
> > tp->tso_deferred = jiffies;
> >
> > /* this won't defer if jiffies == 0 but it's only a 1 in
> > * 4 billion event (and avoids a branch)
> > */
> > return (jiffies != 0);
>
> I'm not sure how the jiffies work but is this racy as well?
>
> Simple return tp->tso_deferred; should work, shouldn't it? :-)
As long as tp->tso_deferred remains u32, pending the other issue.
-Bill
next prev parent reply other threads:[~2007-12-21 19:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-19 21:46 TSO trimming question Ilpo Järvinen
2007-12-19 22:02 ` Ilpo Järvinen
2007-12-20 3:26 ` Herbert Xu
2007-12-20 7:55 ` David Miller
2007-12-20 7:54 ` David Miller
2007-12-20 11:40 ` Ilpo Järvinen
2007-12-20 11:56 ` David Miller
2007-12-20 16:02 ` John Heffner
2007-12-21 4:36 ` David Miller
2007-12-21 8:06 ` Bill Fink
2007-12-21 9:26 ` Ilpo Järvinen
2007-12-21 9:28 ` Ilpo Järvinen
2007-12-21 9:27 ` David Miller
2007-12-21 9:29 ` Herbert Xu
2007-12-21 9:36 ` David Miller
2007-12-21 10:58 ` Bill Fink
2007-12-21 18:54 ` Bill Fink
2007-12-21 18:58 ` Ilpo Järvinen
2007-12-21 19:37 ` Bill Fink [this message]
2007-12-20 12:00 ` David Miller
2007-12-20 12:35 ` Ilpo Järvinen
2007-12-20 14:00 ` Herbert Xu
2007-12-20 23:55 ` David Miller
2007-12-21 18:55 ` [PATCH] [TCP]: Force TSO splits to MSS boundaries Ilpo Järvinen
2007-12-21 20:01 ` Ilpo Järvinen
2007-12-25 5:35 ` David Miller
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