From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx117.postini.com [74.125.245.117]) by kanga.kvack.org (Postfix) with SMTP id 7F5226B0002 for ; Wed, 24 Apr 2013 02:11:20 -0400 (EDT) Received: by mail-ie0-f177.google.com with SMTP id 9so1610193iec.8 for ; Tue, 23 Apr 2013 23:11:19 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <517726C8.4030207@linaro.org> References: <516EE256.2070303@linaro.org> <5175FBEB.4020809@linaro.org> <517726C8.4030207@linaro.org> Date: Wed, 24 Apr 2013 10:11:19 +0400 Message-ID: Subject: Re: Summary of LSF-MM Volatile Ranges Discussion From: Dmitry Vyukov Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: John Stultz Cc: lsf@lists.linux-foundation.org, linux-mm@kvack.org, Minchan Kim , Paul Turner , Robert Love , Dave Hansen , Taras Glek , Mike Hommey , Kostya Serebryany , Hugh Dickins , Michel Lespinasse , KOSAKI Motohiro , Johannes Weiner , Greg Thelen , Rik van Riel , glommer@parallels.com, mhocko@suse.de On Wed, Apr 24, 2013 at 4:26 AM, John Stultz wrote: > On 04/22/2013 11:51 PM, Dmitry Vyukov wrote: >> >> Just want to make sure our case does not fall out of the discussion: >> https://code.google.com/p/thread-sanitizer/wiki/VolatileRanges > > > Yes, while I forgot to mention it in the summary, I did bring it up briefly, > but I cannot claim to have done it justice. Thanks! > Personally, while I suspect we might be able to support your desired > semantics (ie: mark once volatile, always zero-fill, no sigbus) via a mode > flag > > >> While reading your email, I remembered that we actually have some >> pages mapped from a file inside the range. So it's like 70TB of ANON >> mapping + few pages in the middle mapped from FILE. The file is mapped >> with MAP_PRIVATE + PROT_READ, it's read-only and not shared. >> But we want to mark the volatile range only once on startup, so >> performance is not a serious concern (while the function in executed >> in say no more than 10ms). >> If the mixed ANON+FILE ranges becomes a serious problem, we are ready >> to remove FILE mappings, because it's only an optimization. I.e. we >> can make it pure ANON mapping. > > Well, in my mind, the MAP_PRIVATE mappings are semantically the same as > anonymous memory with regards to volatility. So I hope this wouldn't be an > issue. Ah, I see, so you more concerned about SHARED rather than FILE. We do NOT have any SHARED regions. -- 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