From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Turner Subject: Re: [PATCH v5 02/15] read-cache: allow to keep mmap'd memory after reading Date: Wed, 20 Apr 2016 15:43:15 -0400 Organization: Twitter Message-ID: <1461181395.5540.170.camel@twopensource.com> References: <1461108489-29376-1-git-send-email-dturner@twopensource.com> <1461108489-29376-3-git-send-email-dturner@twopensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Git Mailing List To: Duy Nguyen X-From: git-owner@vger.kernel.org Wed Apr 20 21:43:47 2016 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1asy2I-0000QW-Vw for gcvg-git-2@plane.gmane.org; Wed, 20 Apr 2016 21:43:43 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751849AbcDTTna convert rfc822-to-quoted-printable (ORCPT ); Wed, 20 Apr 2016 15:43:30 -0400 Received: from mail-qk0-f176.google.com ([209.85.220.176]:35045 "EHLO mail-qk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751653AbcDTTnR (ORCPT ); Wed, 20 Apr 2016 15:43:17 -0400 Received: by mail-qk0-f176.google.com with SMTP id q76so8032035qke.2 for ; Wed, 20 Apr 2016 12:43:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=twopensource-com.20150623.gappssmtp.com; s=20150623; h=message-id:subject:from:to:cc:date:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=tYs4vwWoRZnXYNM16n4P0dzP7vwdZIh3VFsLl7sfNDs=; b=PoRBVrb2uty9H2L6xVenyDiO+n9rMPDm+TvBaCNCSx2VFakGMQl+NXLFv5xZ8DdfOu cIdx2PCIdGtMOpWd5QHEk8P48u7iTc3hGDc9QbHRUfnE2yMpgK38C937zqdQlE0O/R9z 37yrAoxyTnaU0IjgqLJXdTzkWil6JaGa0Dax4wV6CEfkf9WwLAPcGDQfqE4q7/dbkXbP bK2FenmvWCM4zWpFR2E8DtaX+9mkLPI2+37YqDdkv6EEWrsCViZ8EDRnsAT2+EhB7N/9 cjePcdM6TEj1plvce5D1YNighE2OBdlax8ZWyizLnDMu+2E5V2quQxa8RNtcOBgAUS0P vnpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=tYs4vwWoRZnXYNM16n4P0dzP7vwdZIh3VFsLl7sfNDs=; b=mtMBXYA+7sxYxrSGjBB99AAYkMLx95Zf7qlk/ugfl4KN4veAL8Ey8hVqJX445xKdQq e7eq0y3d52nzXXX5EEpdGbQMLllxGv7WAfYpKaMSslW+UFdUFNjdaYwsDvWZABg5cyA7 EvF2Wh7L1m5ozfcd8vfFAUQv+AOj5ZlLtyf66m2fK1Kqx6k7wBgxof3omrihGFdLuIOT yc5EbwtZaOYaZb8cqVxU8+XtuoyIPCDVFxy5FsjTTgt4dGcsf+mpQGdcCzXmZxYq6s5L j5SrEZ1ezOqHbZQhcEyu7f9yRsShe4PDQAuL4x/BSMswDM7JSdrPeUjmOOW8VbDIzjlv VtJA== X-Gm-Message-State: AOPr4FWLJzW+X3w8ODi/vZu+jECZHFFWTJvlKsJVQUab7rH8Mte6sumBbqd5YgctBgjRkw== X-Received: by 10.55.33.5 with SMTP id h5mr4626234qkh.99.1461181396440; Wed, 20 Apr 2016 12:43:16 -0700 (PDT) Received: from ubuntu (207-38-164-98.c3-0.43d-ubr2.qens-43d.ny.cable.rcn.com. [207.38.164.98]) by smtp.gmail.com with ESMTPSA id c193sm9343624qkg.43.2016.04.20.12.43.15 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 20 Apr 2016 12:43:15 -0700 (PDT) In-Reply-To: X-Mailer: Evolution 3.16.5-1ubuntu3.1 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Wed, 2016-04-20 at 16:26 +0700, Duy Nguyen wrote: > On Wed, Apr 20, 2016 at 6:27 AM, David Turner < > dturner@twopensource.com> wrote: > > From: Nguy=E1=BB=85n Th=C3=A1i Ng=E1=BB=8Dc Duy > >=20 > > Later, we will introduce git index-helper to share this memory with > > other git processes. > >=20 > > Since the memory will be shared, it will never be unmapped > > (although > > the kernel may of course choose to page it out). >=20 > This is not entirely true. We do need to keep the mmap'd memory for > longer, even after read_index_from() finishes. But we do not share > the > exact same address space to other processes (memcpy is used in > index-helper.c:share_index()). We could even discard_index() at the > end of share_index(), but I think we keep it anyway just in case > another process asks, or when index is not updated. Will reword.