Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933312AbbESOTv (ORCPT ); Tue, 19 May 2015 10:19:51 -0400 Received: from smtp.citrix.com ([66.165.176.89]:2450 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932509AbbESOTt (ORCPT ); Tue, 19 May 2015 10:19:49 -0400 X-IronPort-AV: E=Sophos;i="5.13,458,1427760000"; d="scan'208";a="264029483" Message-ID: <555B45A1.4070604@citrix.com> Date: Tue, 19 May 2015 15:16:01 +0100 From: Julien Grall User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: Boris Ostrovsky , Julien Grall , CC: , Konrad Rzeszutek Wilk , , , , David Vrabel , Subject: Re: [RFC 10/23] xen/biomerge: WORKAROUND always says the biovec are not mergeable References: <1431622863-28575-1-git-send-email-julien.grall@citrix.com> <1431622863-28575-11-git-send-email-julien.grall@citrix.com> <555616D3.7060603@oracle.com> In-Reply-To: <555616D3.7060603@oracle.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1900 Lines: 56 Hi Boris, On 15/05/15 16:54, Boris Ostrovsky wrote: > On 05/14/2015 01:00 PM, Julien Grall wrote: >> When Linux is using 64K page granularity, every page will be slipt in >> multiple non-contiguous 4K MFN. >> >> I'm not sure how to handle efficiently the check to know whether we can >> merge 2 biovec with a such case. So for now, always says that biovec are >> not mergeable. >> >> Signed-off-by: Julien Grall >> Cc: Konrad Rzeszutek Wilk >> Cc: Boris Ostrovsky >> Cc: David Vrabel >> --- >> drivers/xen/biomerge.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c >> index 0edb91c..20387c2 100644 >> --- a/drivers/xen/biomerge.c >> +++ b/drivers/xen/biomerge.c >> @@ -9,6 +9,9 @@ bool xen_biovec_phys_mergeable(const struct bio_vec >> *vec1, >> unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page)); >> unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page)); >> + /* TODO: Implement it correctly */ >> + return 0; >> + >> return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) && >> ((mfn1 == mfn2) || ((mfn1+1) == mfn2)); >> } > > > I think this is a bit too blunt. Perhaps check first whether page sizes > are different in the hypervisor and the guest? Sounds good. > > (And I am not sure we need __BIOVEC_PHYS_MERGEABLE() test here as it is > already checked by BIOVEC_PHYS_MERGEABLE() which appears to be the only > user of xen_biovec_phys_mergeable()) I can send a patch to drop __BIOVEC_PHYS_MERGEABLE. Regards, -- Julien Grall -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/