From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?= Subject: [PATCH] index-pack: reduce memory footprint a bit Date: Mon, 9 Feb 2015 20:18:49 +0700 Message-ID: <1423487929-28019-1-git-send-email-pclouds@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: msporleder@gmail.com, =?UTF-8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?= To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Mon Feb 09 14:18:56 2015 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 1YKoEp-0003Uo-6e for gcvg-git-2@plane.gmane.org; Mon, 09 Feb 2015 14:18:55 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760277AbbBINSv convert rfc822-to-quoted-printable (ORCPT ); Mon, 9 Feb 2015 08:18:51 -0500 Received: from mail-pa0-f45.google.com ([209.85.220.45]:57447 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759865AbbBINSu (ORCPT ); Mon, 9 Feb 2015 08:18:50 -0500 Received: by mail-pa0-f45.google.com with SMTP id et14so33837722pad.4 for ; Mon, 09 Feb 2015 05:18:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-type:content-transfer-encoding; bh=2OfRcCmiOR0Mo3wj/VEJys5e6aQshGqC5aFloiCiZTs=; b=BwioZfYCZ97kuzZ8xqkaK8SQWItGEtKY10wcjCPpNDZS0IT2Bbxv25s431ToVY5GZY SMO70wcwRxG9ulCT/sMokWnrmnA/AYeIS2dzl09dwhN9DLTj7Lg++YB9w//G6JEotNra akU1HCQ8nTT7CTciYbKHJwwIpVUW5/gtsMhwiKOkjOdJMytC56KTgpQ5rMQaAFasTKNf Nl/aM7HE0uOrUhbKukqiLNSf/MKTGiJM1EMGAa66Qb5MNecflZCT6p4Q1a+WBSrqYAP2 9ODNvn1p8Zl2jxcXYdKxXCNQyPJLL0gJgK9JQl5OSvO8tievq1jcS+B5TJv959a0pVb1 xidg== X-Received: by 10.66.55.41 with SMTP id o9mr28484816pap.80.1423487929692; Mon, 09 Feb 2015 05:18:49 -0800 (PST) Received: from lanh ([115.73.243.52]) by mx.google.com with ESMTPSA id ms9sm16403020pdb.41.2015.02.09.05.18.46 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Feb 2015 05:18:48 -0800 (PST) Received: by lanh (sSMTP sendmail emulation); Mon, 09 Feb 2015 20:18:56 +0700 X-Mailer: git-send-email 2.3.0.rc1.137.g477eb31 In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: =46or each object in the input pack, we need one struct object_entry. O= n x86-64, this struct is 64 bytes long. Although: - The 8 bytes for delta_depth and base_object_no are only useful when show_stat is set. And it's never set unless someone is debugging. - The three fields hdr_size, type and real_type take 4 bytes each even though they never use more than 4 bits. By moving delta_depth and base_object_no out of struct object_entry and make the other 3 fields one byte long instead of 4, we shrink 25% of this struct. On a 3.4M object repo that's about 53MB. The saving is less impressive compared to index-pack total memory use (about 400MB before delta resolving, so the saving is just 13%) Signed-off-by: Nguy=E1=BB=85n Th=C3=A1i Ng=E1=BB=8Dc Duy --- I'm not sure if this patch is worth pursuing. It makes the code a little bit harder to read. I was just wondering how much memory could be saved.. We could maybe save some more by splitting union delta_base with the assumption that pack-objects would utilize delta-ofs-offset as much as possible, which makes the delta_base.sha1[] a waste most of the time. =20 This repo has 2803447 deltas, and because it's a clone case, all delta should be ofs-delta, which means we waste about 32MB. But shrinking this could get ugly. builtin/index-pack.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/builtin/index-pack.c b/builtin/index-pack.c index 4632117..479ec5e 100644 --- a/builtin/index-pack.c +++ b/builtin/index-pack.c @@ -18,9 +18,12 @@ static const char index_pack_usage[] =3D struct object_entry { struct pack_idx_entry idx; unsigned long size; - unsigned int hdr_size; - enum object_type type; - enum object_type real_type; + unsigned char hdr_size; + char type; + char real_type; +}; + +struct object_entry_extra { unsigned delta_depth; int base_object_no; }; @@ -64,6 +67,7 @@ struct delta_entry { }; =20 static struct object_entry *objects; +static struct object_entry_extra *objects_extra; static struct delta_entry *deltas; static struct thread_local nothread_data; static int nr_objects; @@ -873,13 +877,15 @@ static void resolve_delta(struct object_entry *de= lta_obj, void *base_data, *delta_data; =20 if (show_stat) { - delta_obj->delta_depth =3D base->obj->delta_depth + 1; + int i =3D delta_obj - objects; + int j =3D base->obj - objects; + objects_extra[i].delta_depth =3D objects_extra[j].delta_depth + 1; deepest_delta_lock(); - if (deepest_delta < delta_obj->delta_depth) - deepest_delta =3D delta_obj->delta_depth; + if (deepest_delta < objects_extra[i].delta_depth) + deepest_delta =3D objects_extra[i].delta_depth; deepest_delta_unlock(); + objects_extra[i].base_object_no =3D j; } - delta_obj->base_object_no =3D base->obj - objects; delta_data =3D get_data_from_pack(delta_obj); base_data =3D get_base_data(base); result->obj =3D delta_obj; @@ -902,7 +908,7 @@ static void resolve_delta(struct object_entry *delt= a_obj, * "want"; if so, swap in "set" and return true. Otherwise, leave it u= ntouched * and return false. */ -static int compare_and_swap_type(enum object_type *type, +static int compare_and_swap_type(char *type, enum object_type want, enum object_type set) { @@ -1499,7 +1505,7 @@ static void show_pack_info(int stat_only) struct object_entry *obj =3D &objects[i]; =20 if (is_delta_type(obj->type)) - chain_histogram[obj->delta_depth - 1]++; + chain_histogram[objects_extra[i].delta_depth - 1]++; if (stat_only) continue; printf("%s %-6s %lu %lu %"PRIuMAX, @@ -1508,8 +1514,8 @@ static void show_pack_info(int stat_only) (unsigned long)(obj[1].idx.offset - obj->idx.offset), (uintmax_t)obj->idx.offset); if (is_delta_type(obj->type)) { - struct object_entry *bobj =3D &objects[obj->base_object_no]; - printf(" %u %s", obj->delta_depth, sha1_to_hex(bobj->idx.sha1)); + struct object_entry *bobj =3D &objects[objects_extra[i].base_object= _no]; + printf(" %u %s", objects_extra[i].delta_depth, sha1_to_hex(bobj->id= x.sha1)); } putchar('\n'); } @@ -1672,6 +1678,8 @@ int cmd_index_pack(int argc, const char **argv, c= onst char *prefix) curr_pack =3D open_pack_file(pack_name); parse_pack_header(); objects =3D xcalloc(nr_objects + 1, sizeof(struct object_entry)); + if (show_stat) + objects_extra =3D xcalloc(nr_objects + 1, sizeof(struct object_entry= _extra)); deltas =3D xcalloc(nr_objects, sizeof(struct delta_entry)); parse_pack_objects(pack_sha1); resolve_deltas(); --=20 2.3.0.rc1.137.g477eb31