From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15244 invoked by alias); 12 Aug 2013 17:20:01 -0000 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org Received: (qmail 15121 invoked by uid 48); 12 Aug 2013 17:19:58 -0000 From: "tudorb at gmail dot com" To: glibc-bugs@sourceware.org Subject: [Bug libc/12518] memcpy acts randomly (and differently) with overlapping areas Date: Mon, 12 Aug 2013 17:20:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: libc X-Bugzilla-Version: 2.13 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: tudorb at gmail dot com X-Bugzilla-Status: RESOLVED X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: drepper.fsp at gmail dot com X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2013-08/txt/msg00042.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=12518 Tudor Bosman changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |tudorb at gmail dot com --- Comment #28 from Tudor Bosman --- FYI, this bug has bitten me in a different way: memcpy() copying backwards defeats the MADV_SEQUENTIAL flag to madvise(). A trivial file copier implementation (mmap source, mmap destination, set MADV_SEQUENTIAL, memcpy from source to destination) would perform much worse on machines that support SSSE3 than on machines that don't because of this bug. (Before anyone tells me that I should copy files using read() and write(), my actual usage pattern was more complex, but the details are irrelevant.) -- You are receiving this mail because: You are on the CC list for the bug.