From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KzNrL-0003TS-4h for qemu-devel@nongnu.org; Sun, 09 Nov 2008 22:54:39 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KzNrJ-0003TB-Dq for qemu-devel@nongnu.org; Sun, 09 Nov 2008 22:54:38 -0500 Received: from [199.232.76.173] (port=43675 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KzNrJ-0003T8-Bm for qemu-devel@nongnu.org; Sun, 09 Nov 2008 22:54:37 -0500 Received: from rv-out-0708.google.com ([209.85.198.248]:41459) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1KzNrJ-0004k4-5a for qemu-devel@nongnu.org; Sun, 09 Nov 2008 22:54:37 -0500 Received: by rv-out-0708.google.com with SMTP id f25so2183636rvb.22 for ; Sun, 09 Nov 2008 19:54:35 -0800 (PST) Message-ID: Date: Mon, 10 Nov 2008 04:54:35 +0100 From: "andrzej zaborowski" Subject: Re: [Qemu-devel] [PATCH, v2] Rewrite mmap_find_vma() to work fine on 64-bit hosts with 32-bit targets In-Reply-To: <20081101165543.GA5076@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1223892640-15545-11-git-send-email-kirill@shutemov.name> <1225129768-11603-1-git-send-email-kirill@shutemov.name> <20081101165110.GA6991@shareable.org> <20081101165543.GA5076@localhost.localdomain> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Hi, 2008/11/1 Kirill A. Shutemov : > On Sat, Nov 01, 2008 at 04:51:10PM +0000, Jamie Lokier wrote: >> Kirill A. Shutemov wrote: >> > + /* Unmap and try again with new page */ >> > + munmap(ptr, size); >> > addr += qemu_host_page_size; >> >> Won't this be rather slow if it has to skip a large mapped area, one >> page at a time? > > If we skip more than one page we increase memory fragmentation. This approach makes sense, however the iterating over all pages may indeed have performance consequences, plus it would be great if people who better know linux-user/ than me commented. I'll assume that everyone is happy with this otherwise. It may be useful adding a comment on top of the function that it must be called with mmap_lock held. Cheers