From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Tejun Heo <htejun@gmail.com>
Cc: ntl@pobox.com, viro@ftp.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] big reader semaphore take#2
Date: Sat, 05 Nov 2005 11:14:25 +1100 [thread overview]
Message-ID: <436BF961.9070402@yahoo.com.au> (raw)
In-Reply-To: <436B79BA.6070300@gmail.com>
Tejun Heo wrote:
> Tejun Heo wrote:
>
>> Hello guys,
>>
>> This is the second take of brsem (big reader semaphore).
>>
>> Nick, unfortunately, simple array of rwsem's does not work as lock
>> holders are not pinned down to cpus and may release locks on other
>> cpus.
>>
[...]
>
> (Nick, what do you think about the new implementation?)
>
As I said, I think I'd prefer to see an implementation that returns
a token from down_read to be used in up_read (ie. the slot # of the
counter which has been downed).
This obviously no longer makes it a drop in replacement for an rwsem.
But could such a beast ever be considered so? Would that make your
VFS patches really ugly?
The upshot of that would be that you could build the whole thing
from rwsem infrastructure and have basically zero other locking
mechanisms or complexity that you don't want in a synchronisation
primitive.
Nick
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2005-11-05 0:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-28 10:44 [PATCH RFC] big reader semaphore take#2 Tejun Heo
2005-10-28 11:06 ` Nick Piggin
2005-11-04 15:09 ` Tejun Heo
2005-11-05 0:14 ` Nick Piggin [this message]
2005-11-05 1:18 ` Tejun Heo
2005-11-05 1:29 ` Nick Piggin
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=436BF961.9070402@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=htejun@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=ntl@pobox.com \
--cc=viro@ftp.linux.org.uk \
/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