From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 15 May 2003 21:19:21 +0200 From: Andrea Arcangeli Subject: Re: Race between vmtruncate and mapped areas? Message-ID: <20030515191921.GJ1429@dualathlon.random> References: <20030513181018.4cbff906.akpm@digeo.com> <18240000.1052924530@baldur.austin.ibm.com> <20030514103421.197f177a.akpm@digeo.com> <82240000.1052934152@baldur.austin.ibm.com> <20030515004915.GR1429@dualathlon.random> <20030515013245.58bcaf8f.akpm@digeo.com> <20030515085519.GV1429@dualathlon.random> <20030515022000.0eb9db29.akpm@digeo.com> <20030515094041.GA1429@dualathlon.random> <1053016706.2693.10.camel@ibm-c.pdx.osdl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1053016706.2693.10.camel@ibm-c.pdx.osdl.net> Sender: owner-linux-mm@kvack.org Return-Path: To: Daniel McNeil Cc: Andrew Morton , dmccr@us.ibm.com, mika.penttila@kolumbus.fi, linux-mm@kvack.org, Linux Kernel Mailing List List-ID: On Thu, May 15, 2003 at 09:38:26AM -0700, Daniel McNeil wrote: > On Thu, 2003-05-15 at 02:40, Andrea Arcangeli wrote: > > On Thu, May 15, 2003 at 02:20:00AM -0700, Andrew Morton wrote: > > > Andrea Arcangeli wrote: > > > > > > > > and it's still racy > > > > > > damn, and it just booted ;) > > > > > > I'm just a little bit concerned over the ever-expanding inode. Do you > > > think the dual sequence numbers can be replaced by a single generation > > > counter? > > > > yes, I wrote it as a single counter first, but was unreadable and it had > > more branches, so I added the other sequence number to make it cleaner. > > I don't mind another 4 bytes, that cacheline should be hot anyways. > > You could use the seqlock.h sequence locking. It only uses 1 sequence > counter. The 2.5 isize patch 1 has a sequence lock without the spinlock > so it only uses 4 bytes and it is somewhat more readable. I don't > think it has more branches. > > I've attached the isize seqlock.h patch. what do you think of the rmb vs mb in the reader side? Can I use rmb too? I used mb() to go safe. I mean gettimeofday is a no brainer since it does only reads inside the critical section anyways. But here I feel I need mb(). And yes, there are no more branches sorry, just an additional or. Andrea -- 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: aart@kvack.org