From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Gerst Date: Thu, 14 Oct 2004 17:30:21 +0000 Subject: Re: [PATCH] General purpose zeroed page slab Message-Id: <416EB7AD.4040302@didntduck.org> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Martin K. Petersen" Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, akpm@osdl.org, tony.luck@intel.com Martin K. Petersen wrote: > A while back Bill Irwin converted the page table code on ppc64 to use > a zeroed page slab. I recently did the same on ia64 and got a > significant performance improvement in terms of fault time (4 usec -> > 700 nsec). > > This cache needs to be initialized fairly early on and so far we've > called it from pgtable_cache_init() on both archs. However, Tony Luck > thought it might be useful to have a general purpose slab cache with > zeroed pages. And other architectures might decide to use it for > their page tables too. > > Consequently here's a patch that puts this functionality in slab.c. > > Signed-off-by: Martin K. Petersen > This doesn't work as you expect it does. The constructor is only called when a new slab is created, for each new object on the slab. It is _not_ run again when an object is freed. So if a page is freed then immediately reallocated it will contain garbage. -- Brian Gerst