From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from flinx.npwt.net (eric@flinx.npwt.net [208.236.161.237]) by kvack.org (8.8.7/8.8.7) with ESMTP id KAA28220 for ; Wed, 1 Jul 1998 10:31:04 -0400 Subject: Re: (reiserfs) Re: More on Re: (reiserfs) Reiserfs and ext2fs (was Re: (reiserfs) Sum Benchmarks (these look typical?)) References: <199806221138.MAA00852@dax.dcs.ed.ac.uk> <358F4FBE.821B333C@ricochet.net> <199806241154.MAA03544@dax.dcs.ed.ac.uk> <199806251100.MAA00835@dax.dcs.ed.ac.uk> <199806291035.LAA00733@dax.dcs.ed.ac.uk> <199806301610.RAA00957@dax.dcs.ed.ac.uk> <199807010912.KAA00789@dax.dcs.ed.ac.uk> From: ebiederm+eric@npwt.net (Eric W. Biederman) Date: 01 Jul 1998 08:11:46 -0500 In-Reply-To: "Stephen C. Tweedie"'s message of Wed, 1 Jul 1998 10:12:40 +0100 Message-ID: Sender: owner-linux-mm@kvack.org To: "Stephen C. Tweedie" Cc: Hans Reiser , Shawn Leas , Reiserfs , Ken Tetrick , linux-mm@kvack.org List-ID: >>>>> "ST" == Stephen C Tweedie writes: ST> Hi, ST> On 30 Jun 1998 19:17:15 -0500, ebiederm+eric@npwt.net (Eric ST> W. Biederman) said: >> When either I trace through the code, or a hardware guy convinces me, >> that it is safe to both write to a page, and do DMA from a page >> simultaneously I'll believe it. ST> Read the source code! We already do this. If one process or thread ST> msync()s a mapped file, its dirty pages get written to disk, ST> independently of any other processes on the same or other CPUs which ST> may still have the pages mapped and may still be writing to them. We ST> don't unmap pages for write; we just mark them non-dirty around all ST> ptes. I just took the time and looked. And in buffer.c in get_hash_table if we are returning a locked buffer, we always wait on that buffer until it is unlocked. So to date we I don't see us tempting fate, with writing to locked buffers. It may be harmless but I have't seen that yet. Eric