Re: [patch 2/3] mm: speculative get_page

All of lore.kernel.org
 help / color / mirror / Atom feed

From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <npiggin@suse.de>, Andrew Morton <akpm@osdl.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Memory Management <linux-mm@kvack.org>
Subject: Re: [patch 2/3] mm: speculative get_page
Date: Wed, 05 Apr 2006 10:22:30 +1000	[thread overview]
Message-ID: <44330DC6.1040805@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0604040814140.26807@schroedinger.engr.sgi.com>

Christoph Lameter wrote:
> Looks like the NoNewRefs flag is mostly == 
> spin_is_locked(mapping->tree_lock)? Would it not be better to check the 
> tree_lock?
> 

Well there are other uses for the tree_lock (eg. tag operations)
which do not need the "no new references" guarantee.

> 
> 
>>--- linux-2.6.orig/mm/migrate.c
>>+++ linux-2.6/mm/migrate.c
>> 
>>+	SetPageNoNewRefs(page);
>> 	write_lock_irq(&mapping->tree_lock);
> 
> 
> A dream come true! If this is really working as it sounds then we can 
> move the SetPageNoNewRefs up and avoid the final check under 
> mapping->tree_lock. Then keep SetPageNoNewRefs until the page has been 
> copied. It would basically play the same role as locking the page.
> 

Yes we could do that but at this stage I wouldn't like to seperate
SetPageNoNewRefs from tree_lock, as it is replacing a traditional
guarantee that tree_lock no longer provides.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com

WARNING: multiple messages have this Message-ID (diff)

From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <npiggin@suse.de>, Andrew Morton <akpm@osdl.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Memory Management <linux-mm@kvack.org>
Subject: Re: [patch 2/3] mm: speculative get_page
Date: Wed, 05 Apr 2006 10:22:30 +1000	[thread overview]
Message-ID: <44330DC6.1040805@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0604040814140.26807@schroedinger.engr.sgi.com>

Christoph Lameter wrote:
> Looks like the NoNewRefs flag is mostly == 
> spin_is_locked(mapping->tree_lock)? Would it not be better to check the 
> tree_lock?
> 

Well there are other uses for the tree_lock (eg. tag operations)
which do not need the "no new references" guarantee.

> 
> 
>>--- linux-2.6.orig/mm/migrate.c
>>+++ linux-2.6/mm/migrate.c
>> 
>>+	SetPageNoNewRefs(page);
>> 	write_lock_irq(&mapping->tree_lock);
> 
> 
> A dream come true! If this is really working as it sounds then we can 
> move the SetPageNoNewRefs up and avoid the final check under 
> mapping->tree_lock. Then keep SetPageNoNewRefs until the page has been 
> copied. It would basically play the same role as locking the page.
> 

Yes we could do that but at this stage I wouldn't like to seperate
SetPageNoNewRefs from tree_lock, as it is replacing a traditional
guarantee that tree_lock no longer provides.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

next prev parent reply	other threads:[~2006-04-05 23:49 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-04-04  9:31 [patch 0/3] lockless pagecache Nick Piggin
2006-04-04  9:31 ` Nick Piggin
2006-04-04  9:31 ` [patch 1/3] radix tree: RCU lockless read-side Nick Piggin
2006-04-04  9:31   ` Nick Piggin
2006-04-04  9:32 ` [patch 2/3] mm: speculative get_page Nick Piggin
2006-04-04  9:32   ` Nick Piggin
2006-04-04  9:47   ` Andrew Morton
2006-04-04  9:47     ` Andrew Morton
2006-04-04 10:21     ` Nick Piggin
2006-04-04 10:21       ` Nick Piggin
2006-04-04 15:20   ` Christoph Lameter
2006-04-04 15:20     ` Christoph Lameter
2006-04-05  0:22     ` Nick Piggin [this message]
2006-04-05  0:22       ` Nick Piggin
2006-04-04 15:21   ` Christoph Lameter
2006-04-04 15:21     ` Christoph Lameter
2006-04-05  0:27     ` Nick Piggin
2006-04-05  0:27       ` Nick Piggin
2006-04-04  9:32 ` [patch 3/3] mm: lockless pagecache lookups Nick Piggin
2006-04-04  9:32   ` Nick Piggin
  -- strict thread matches above, loose matches on Subject: below --
2006-03-10 15:18 A lockless pagecache for Linux Nick Piggin
2006-03-10 15:18 ` [patch 2/3] mm: speculative get_page Nick Piggin
2006-03-10 15:18   ` 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=44330DC6.1040805@yahoo.com.au \
    --to=nickpiggin@yahoo.com.au \
    --cc=akpm@osdl.org \
    --cc=clameter@sgi.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=npiggin@suse.de \
    /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.