From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ilya Loginov Subject: Re: problems in commit 2d4dc890b5c8 (block: add helpers to run flush_dcache_page() against a bio and a request's pages) Date: Thu, 10 Dec 2009 03:06:38 +0300 Message-ID: <20091210030638.db4cfd8a.isloginov@gmail.com> References: <1260398346.14369.45.camel@mulgrave.site> <20091210020309.36742c7f.isloginov@gmail.com> <1260400273.14369.52.camel@mulgrave.site> <20091210023609.b8c9bd34.isloginov@gmail.com> <1260402471.14369.60.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ew0-f209.google.com ([209.85.219.209]:43257 "EHLO mail-ew0-f209.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758856AbZLJAGf (ORCPT ); Wed, 9 Dec 2009 19:06:35 -0500 Received: by ewy1 with SMTP id 1so5045997ewy.28 for ; Wed, 09 Dec 2009 16:06:40 -0800 (PST) In-Reply-To: <1260402471.14369.60.camel@mulgrave.site> Sender: linux-arch-owner@vger.kernel.org List-ID: To: James Bottomley Cc: Jens Axboe , linux-arch@vger.kernel.org On Wed, 09 Dec 2009 17:47:51 -0600 James Bottomley wrote: > Which architecture is this? ... because if it's missing a necessary > definition for flush_kernel_dcache_page() it's very easy to add it ... This is a MIPS. Why? The call flush_dcache_page() on MIPS is lazy enought. And it do exactly what i need to fix the problem. > > But. I could do that rq_flush_dcache_pages will call flush_kernel_dcache_page > > for architectures where ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE was defined. > > The point I'm trying to make is that flush_dcache_page() does a lot of > unnecessary flushing. Where you are in the system with the READ call, > you know the user aliases are clean (because users aren't allowed to > touch pages submitted for write), so you only (for efficiency) need to > flush the dirty kernel alias. I understand that in your case(parisc) solution with flushdcache_page() is very voracious. But I don't think that we should change something somewhere else except parisc. Or we should write to Ralf Baechle and other maintainers and discuss all with them. Don't think? -- Ilya Loginov