Date: Tue, 2 Nov 2004 20:39:01 +0100
From: Andrea Arcangeli <andrea@novell.com>
To: Andy Whitcroft <apw@shadowen.org>
Cc: "Martin J. Bligh" <mbligh@aracnet.com>, Andrew Morton <akpm@osdl.org>,
       nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org
Subject: Re: PG_zero
Message-ID: <20041102193901.GO3571@dualathlon.random>
References: <20041030141059.GA16861@dualathlon.random> <20041030140732.2ccc7d22.akpm@osdl.org> <40860000.1099235861@[10.10.2.4]> <41879145.7090309@shadowen.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <41879145.7090309@shadowen.org>
User-Agent: Mutt/1.5.6i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1600
Lines: 29

On Tue, Nov 02, 2004 at 01:53:09PM +0000, Andy Whitcroft wrote:
> I'll have a look out for the results, they should be around somewhere?

could you give an hint on which workload to use for the measurements?

> page for use.  The colder the page the slower the system went.

this is expected. This is why I waste no more than 4k of cache for each
local-apic irq, and this is also why I don't waste any cache at all if
the zerolist is already full or the hot-cold list is empty (plus if
there are PG_zero pages in the hot-cold list since I cache PG_zere deep
down in the buddy, I don't waste any cache at all by refiling them into
the zero quicklist). Not sure if you were using the same design. Note
that idle zeroing is a worthless feature in my patch, I never intented
to implement it, I just happened to be able to implement it with a
trivial change so I did (and it can be disabled via sysctl). all the
important stuff are bugfixes and obsoleting the inefficient slab for pte
allocation and to create a superset of the pte_quicklist in 2.4 that is
missing in 2.6 by mistake.

Note that I'm keeping track of hot and cold cache for the zerolist too.
Plus I can disable the idle zeroing and still I will be able to cache
zero information in O(1) (so then caching zero will be zerocost, plus
I'll keep track of the hottest zero page, and the coldest one).
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/