Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932283AbVKKCuP (ORCPT ); Thu, 10 Nov 2005 21:50:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932289AbVKKCuO (ORCPT ); Thu, 10 Nov 2005 21:50:14 -0500 Received: from smtp-out.google.com ([216.239.45.12]:27771 "EHLO smtp-out.google.com") by vger.kernel.org with ESMTP id S932283AbVKKCuN (ORCPT ); Thu, 10 Nov 2005 21:50:13 -0500 Message-ID: <437406D4.4060304@google.com> Date: Thu, 10 Nov 2005 18:49:56 -0800 From: Arun Sharma User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051011) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton CC: rohit.seth@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Expose SHM_HUGETLB in shmctl(id, IPC_STAT, ...) References: <20051109184623.GA21636@sharma-home.net> <20051109222223.538309e4.akpm@osdl.org> <43739302.1080404@google.com> <20051110115941.1cbe1ae7.akpm@osdl.org> <4373BE8D.2070104@google.com> <20051110140621.47729c5b.akpm@osdl.org> In-Reply-To: <20051110140621.47729c5b.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1520 Lines: 39 Andrew Morton wrote: >>>How important is this feature? >> >>Without this feature, an application has no way to figure out if a given >>segment is hugetlb or not. Applications need to know this to be able to >>handle alignment issues properly. >> >>Also, if the flag is exported via ipcs, the system administrator would >>have a better idea about how the hugetlb pages she configured on the >>system are getting used. >> > > > I'd suggest that any API which allows us to query the hugeness of a piece > of memory should also work for mmap(hugetld_fd...). IOW: this capability > shouldn't be restricted to sysv shm areas. The capability I was talking about was the ability to figure out where the configured hugetlb pages are going (vs is this a hugetlb page?). I suspect that one can use lsof+/proc/pid/maps and look for hugetlbfs mount points to gather that data. But for shared memory hugepages, we don't have a way. > But then again, if it was possible to write 100 lines of userspace code, we > wouldn't need this capability at all. I bet if the userspace guys tried a > bit harder they'd work out a way of teaching their applications to remember > what they did. Why do we need shmctl(IPC_STAT) then? Applications should remember what they did :) -Arun - 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/