Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933329Ab3GLW6a (ORCPT ); Fri, 12 Jul 2013 18:58:30 -0400 Received: from mail-pd0-f175.google.com ([209.85.192.175]:60755 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757856Ab3GLW62 (ORCPT ); Fri, 12 Jul 2013 18:58:28 -0400 Date: Fri, 12 Jul 2013 15:58:38 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: naveen yadav cc: kernelnewbies , linux-kernel@vger.kernel.org Subject: Re: shmem info issue In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1666 Lines: 48 On Fri, 12 Jul 2013, naveen yadav wrote: > Hi All > > I am working on tmpfs. During code analysis I found shmem driver > register itself as tmpfs . > > cat /proc/meminfo Shmem field read NR_SHMEM enum filed and shows used > memory in tmpfs > > > [root@localhost linux-3.8.2]# cat /proc/meminfo | grep -r Shmem > Shmem: 704 kB > [root@localhost linux-3.8.2]# > > include/linux/mmzone.h > enum zone_stat_item { > -----cut here------- > NR_SHMEM, /* shmem pages (included tmpfs/GEM pages > -----cut here > } > > I have the following query > 1-> cat /proc/meminfo | grep -r Shmem show only the used tmpfs memory > or it show used tmpfs memory + mata data also (because I found Shmem > is bit larger then tempfs used memory ) "Shmem" includes only data, not metadata, nor memory currently swapped out. But it includes tmpfs memory, SysV shared memory (from ipc/shm.c), POSIX shared memory (under /dev/shm), and shared anonymous mappings (from mmap of /dev/zero with MAP_SHARED: see call to shmem_zero_setup() from drivers/char/mem.c): whatever allocates pages through mm/shmem.c. > 2-> as per the developer comments NR_SHMEM included tmpfs and GEM > pages whct is Gem pages Ah yes, and the Graphics Execution Manager uses shmem for objects shared with the GPU: see use of shmem_read_mapping_page*() in drivers/gpu/drm/. > 3-> is my above code analysis is correct? I think so. Hugh -- 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/