From: Paul Fulghum <paulkf@microgate.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] TTY flip buffer SMP changes
Date: Fri, 08 Oct 2004 08:35:06 -0500 [thread overview]
Message-ID: <1097242506.2008.30.camel@deimos.microgate.com> (raw)
In-Reply-To: <20041008062650.GC2745@thunk.org>
On Fri, 2004-10-08 at 01:26, Theodore Ts'o wrote:
> Even if kmalloc() isn't as fast using two ring buffers which we flip
> back and forth, CPU's have gotten a lot faster since when I
> implemented the flip buffers some 12 years ago (i.e., 8 Moore law's
> doublings ago).
The sk_buff solution does look attractive,
particularly for high data rates.
It does seem to carry serious overhead (in relation
to ring buffers) for devices with small FIFOs.
At 115200bps, I saw the 16550 driver accumulate
~8 bytes per interrupt. Using 2 sk_buffs per interrupt
means 256 sk_buff allocations to push 1KiB (71ms) of data
to the line discipline. This amounts to ~3600 sk_buff
allocations per second at 115200bps.
--
Paul Fulghum
paulkf@microgate.com
next prev parent reply other threads:[~2004-10-08 13:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-07 19:58 [RFC][PATCH] TTY flip buffer SMP changes Paul Fulghum
2004-10-07 19:37 ` Alan Cox
2004-10-08 6:26 ` Theodore Ts'o
2004-10-08 13:35 ` Paul Fulghum [this message]
2004-10-08 12:51 ` Alan Cox
2004-10-08 15:00 ` Theodore Ts'o
2004-10-09 1:42 ` Benjamin Herrenschmidt
2004-10-10 0:32 ` Alan Cox
2004-10-10 3:26 ` Benjamin Herrenschmidt
2004-10-10 12:49 ` Maciej W. Rozycki
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