Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753148AbbKLGQG (ORCPT ); Thu, 12 Nov 2015 01:16:06 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:34413 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbbKLGQE (ORCPT ); Thu, 12 Nov 2015 01:16:04 -0500 Date: Thu, 12 Nov 2015 15:17:01 +0900 From: Sergey Senozhatsky To: David Rientjes Cc: Sergey Senozhatsky , Sergey Senozhatsky , Andrew Morton , Christoph Lameter , Pekka Enberg , Joonsoo Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] tools/vm/slabinfo: update struct slabinfo members' types Message-ID: <20151112061701.GA498@swordfish> References: <1447162326-30626-1-git-send-email-sergey.senozhatsky@gmail.com> <1447162326-30626-4-git-send-email-sergey.senozhatsky@gmail.com> <20151112011347.GC1651@swordfish> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2282 Lines: 78 On (11/11/15 21:07), David Rientjes wrote: [..] > > > > /* Object size */ > > > > - unsigned long long min_objsize = max, max_objsize = 0, avg_objsize; > > > > + unsigned int min_objsize = UINT_MAX, max_objsize = 0, avg_objsize; > > > > > > > > /* Number of partial slabs in a slabcache */ > > > > unsigned long long min_partial = max, max_partial = 0, > > > > > > avg_objsize should not be unsigned int. > > > > Hm. the assumption is that `avg_objsize' cannot be larger > > than `max_objsize', which is > > `int object_size;' in `struct kmem_cache' from slab_def.h > > and > > `unsigned int object_size;' in `struct kmem_cache' from slab.h. > > > > > > avg_objsize = total_used / total_objects; > > > I'm not sure I clearly understand the problems you're pointing me to. > This has nothing to do with object_size in the kernel. what we have in slabinfo as slab_size(), ->object_size, etc. comming from slub's sysfs attrs: chdir("/sys/kernel/slab") while readdir ... slab->object_size = get_obj("object_size"); slab->slab_size = get_obj("slab_size"); ... and attr show handlers are: ... static ssize_t slab_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->size); } SLAB_ATTR_RO(slab_size); static ssize_t object_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->object_size); } SLAB_ATTR_RO(object_size); ... so those are sprintf("%d") of `struct kmem_cache'-s `int' values. > total_used and total_objects are unsigned long long. yes, that's correct. but `total_used / total_objects' cannot be larger that the size of the largest object, which is represented in the kernel and returned to user space as `int'. it must fit into `unsigned int'. > If you need to convert max_objsize to be unsigned long long as > well, that would be better. ... in case if someday `struct kmem_cache' will be updated to keep `unsigned long' sized objects and sysfs attrs will do sprintf("%lu")? IOW, if slabs will keep objects bigger that 4gig? -ss -- 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/