From: Chris Metcalf <cmetcalf@tilera.com>
To: David Miller <davem@davemloft.net>
Cc: <xiyou.wangcong@gmail.com>, <cypher.w@gmail.com>,
<linux-kernel@vger.kernel.org>, <eric.dumazet@gmail.com>,
<netdev@vger.kernel.org>
Subject: Re: IGMP and rwlock: Dead ocurred again on TILEPro
Date: Thu, 17 Feb 2011 18:04:13 -0500 [thread overview]
Message-ID: <4D5DA96D.5060200@tilera.com> (raw)
In-Reply-To: <20110217.145333.232751283.davem@davemloft.net>
On 2/17/2011 5:53 PM, David Miller wrote:
> From: Chris Metcalf <cmetcalf@tilera.com>
> Date: Thu, 17 Feb 2011 17:49:46 -0500
>
>> The fix is to disable interrupts for the arch_read_lock family of methods.
> How does that help handle the race when it happens between different
> cpus, instead of between IRQ and non-IRQ context on the same CPU?
There's no race in that case, since the lock code properly backs off and
retries until the other cpu frees it. The distinction here is that the
non-IRQ context is "wedged" by the IRQ context.
> Why don't you just use the generic spinlock based rwlock code on Tile,
> since that is all that your atomic instructions can handle
> sufficiently?
The tile-specific code encodes reader/writer information in the same 32-bit
word that the test-and-set instruction manipulates, so it's more efficient
both in space and time. This may not really matter for rwlocks, since no
one cares much about them any more, but that was the motivation.
--
Chris Metcalf, Tilera Corp.
http://www.tilera.com
next prev parent reply other threads:[~2011-02-17 23:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 3:39 Fwd: IGMP and rwlock: Dead ocurred again on TILEPro Cypher Wu
2011-02-17 4:49 ` Américo Wang
2011-02-17 5:04 ` Cypher Wu
2011-02-17 5:42 ` Américo Wang
2011-02-17 5:46 ` David Miller
2011-02-17 6:39 ` Eric Dumazet
2011-02-17 22:49 ` Chris Metcalf
2011-02-17 22:53 ` David Miller
2011-02-17 23:04 ` Chris Metcalf [this message]
2011-02-17 23:11 ` David Miller
2011-02-17 23:18 ` Chris Metcalf
2011-02-18 3:16 ` Cypher Wu
2011-02-18 3:19 ` Cypher Wu
2011-02-18 7:08 ` Cypher Wu
2011-02-18 21:51 ` Chris Metcalf
2011-02-19 4:07 ` Cypher Wu
2011-02-20 13:33 ` Chris Metcalf
2011-03-01 18:30 ` [PATCH] arch/tile: fix deadlock bugs in rwlock implementation Chris Metcalf
2011-02-17 6:42 ` Fwd: IGMP and rwlock: Dead ocurred again on TILEPro Cypher Wu
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=4D5DA96D.5060200@tilera.com \
--to=cmetcalf@tilera.com \
--cc=cypher.w@gmail.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=xiyou.wangcong@gmail.com \
/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).