From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id AE49D6B0313 for ; Thu, 1 Jun 2017 14:37:17 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id j28so52342148pfk.14 for ; Thu, 01 Jun 2017 11:37:17 -0700 (PDT) Received: from mail-pf0-x22f.google.com (mail-pf0-x22f.google.com. [2607:f8b0:400e:c00::22f]) by mx.google.com with ESMTPS id w6si20297582pfk.420.2017.06.01.11.37.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Jun 2017 11:37:17 -0700 (PDT) Received: by mail-pf0-x22f.google.com with SMTP id n23so34506064pfb.2 for ; Thu, 01 Jun 2017 11:37:17 -0700 (PDT) Date: Thu, 1 Jun 2017 11:37:07 -0700 (PDT) From: Hugh Dickins Subject: Re: 4.12-rc ppc64 4k-page needs costly allocations In-Reply-To: Message-ID: References: <87h9014j7t.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Hugh Dickins , Michael Ellerman , "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org On Thu, 1 Jun 2017, Christoph Lameter wrote: > > Ok so debugging was off but the slab cache has a ctor callback which > mandates that the free pointer cannot use the free object space when > the object is not in use. Thus the size of the object must be increased to > accomodate the freepointer. Thanks a lot for working that out. Makes sense, fully understood now, nothing to worry about (though makes one wonder whether it's efficient to use ctors on high-alignment caches; or whether an internal "zero-me" ctor would be useful). Hugh -- 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: email@kvack.org