From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shaohua Li , Rik van Riel , Wu Fengguang , Mark Salyzyn , Riley Andrews , Will Deacon Subject: [PATCH 3.14 70/79] arm64: readahead: fault retry breaks mmap file read random detection Date: Sat, 17 Oct 2015 19:06:02 -0700 Message-Id: <20151018020216.437398687@linuxfoundation.org> In-Reply-To: <20151018020213.322172837@linuxfoundation.org> References: <20151018020213.322172837@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Salyzyn commit 569ba74a7ba69f46ce2950bf085b37fea2408385 upstream. This is the arm64 portion of commit 45cac65b0fcd ("readahead: fault retry breaks mmap file read random detection"), which was absent from the initial port and has since gone unnoticed. The original commit says: > .fault now can retry. The retry can break state machine of .fault. In > filemap_fault, if page is miss, ra->mmap_miss is increased. In the second > try, since the page is in page cache now, ra->mmap_miss is decreased. And > these are done in one fault, so we can't detect random mmap file access. > > Add a new flag to indicate .fault is tried once. In the second try, skip > ra->mmap_miss decreasing. The filemap_fault state machine is ok with it. With this change, Mark reports that: > Random read improves by 250%, sequential read improves by 40%, and > random write by 400% to an eMMC device with dm crypto wrapped around it. Cc: Shaohua Li Cc: Rik van Riel Cc: Wu Fengguang Signed-off-by: Mark Salyzyn Signed-off-by: Riley Andrews Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/mm/fault.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -278,6 +278,7 @@ retry: * starvation. */ mm_flags &= ~FAULT_FLAG_ALLOW_RETRY; + mm_flags |= FAULT_FLAG_TRIED; goto retry; } }