From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 30 Apr 2008 08:17:42 +0200 From: Nick Piggin Subject: Re: [rfc] data race in page table setup/walking? Message-ID: <20080430061741.GG27652@wotan.suse.de> References: <20080429050054.GC21795@wotan.suse.de> <20080430060340.GE27652@wotan.suse.de> <20080429.230543.98200575.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080429.230543.98200575.davem@davemloft.net> Sender: owner-linux-mm@kvack.org Return-Path: To: David Miller Cc: hugh@veritas.com, torvalds@linux-foundation.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, benh@kernel.crashing.org List-ID: On Tue, Apr 29, 2008 at 11:05:43PM -0700, David Miller wrote: > From: Nick Piggin > Date: Wed, 30 Apr 2008 08:03:40 +0200 > > > Hardware walkers, I shouldn't worry too much about, except as a thought > > exercise to realise that we have lockless readers. I think(?) alpha can > > walk the linux ptes in hardware on TLB miss, but surely they will have > > to do the requisite barriers in hardware too (otherwise things get > > really messy) > > My understanding is that all Alpha implementations walk the > page tables in PAL code. Ah OK. I guess that's effectively "hardware" as far as Linux is concerned. I guess even x86 really walks the page tables in microcode as well. Basically I just mean something that is invisible to, and obvlivious of, Linux's locking. > > Powerpc's find_linux_pte is one of the software walked lockless ones. > > That's basically how I imagine hardware walkers essentially should operate. > > Sparc64 walks the page tables lockless in it's TLB hash table miss > handling. > > MIPS does something similar. Interesting, thanks. -- 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