From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.7 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 835671F597 for ; Thu, 19 Jul 2018 16:42:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731927AbeGSR0B (ORCPT ); Thu, 19 Jul 2018 13:26:01 -0400 Received: from mail-vk0-f66.google.com ([209.85.213.66]:46662 "EHLO mail-vk0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731663AbeGSR0A (ORCPT ); Thu, 19 Jul 2018 13:26:00 -0400 Received: by mail-vk0-f66.google.com with SMTP id b14-v6so4704441vke.13 for ; Thu, 19 Jul 2018 09:42:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=D1f6zaR2f4KdjFUuyZrYr5VFVq41V+n2K62LUALdT2Q=; b=LkurDVpfjqQvCvsx4anGFkqdNiKu0csaSLWzbx9BxjiUyl9zouFYDkBh96RdMIhbT4 rLg3g7ky6Aa62/pQKfXYg5MgOTL+AZndfavNlSWjlRjksDTEFIL2YnbN0AQ70RjhRbN6 ntpybxinH3aZKBOzCCVsR2VZld5p07Ec8Cnvwx8O8NbJ0nzScXhdCj3iJYvnq2jfb8Y9 1jxJOXimXXcPMhGkC1ukEqUD0WOZjoWnbbFV9tfbH/6dvG5vWGn1OzMiaKvGOcOZb1mK dwpS1dlkCtgCDk/8exqDKWZA0JFpPbEsVgQz6zJgoFHwHnjDX4yxmAKiI8Z6ucXZxcA2 sbyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=D1f6zaR2f4KdjFUuyZrYr5VFVq41V+n2K62LUALdT2Q=; b=Wlafp2ZTGCZQr+f2eLYmzY/4EChTQjd/0964X81U07doEatzUnwGmw6YLaK4tT09Wx cH0RIihBhEQBfe1ZlZo89LtU8a2WP/BsyvD4wWvW7/TVpTU6hkjiO+jJJP3tvMGV2Pbq Su6MzNzO51HXPYQBXZF+5PRVFMNkedIHtC/Z8l0/b1wQPeTO3m//sofFNZdtYBtAR53w 6U2+DyFm5E72NWIf11TsMPa8u+hbKij+KLlSDYE5y7dMEXYcKHXtYP+FaI6pIXU/hzI/ xUCM09UJvPhbXn/IfApbMQsL4wGj7X1oxRAd+nWsZ7bN72st+ZtlShIeXfB2UKWD1y0B G4vQ== X-Gm-Message-State: AOUpUlHwA4NdfRGFFgFoGP1GdzrKEladaAnRM5oRiYi/cgkLP2tf/dYT o4bCwW0d2H9fEzU30XYjIqqS3VYJEIJIZ9I3gzs= X-Google-Smtp-Source: AAOMgpdVcdm7tREuJRv9fEWtI3H756uZ36hfTgKsilEd57pQcH68iXV67s+fnAmhfVmwqhqr70rBlbCaClIuryHPpXs= X-Received: by 2002:a1f:5043:: with SMTP id e64-v6mr6521758vkb.47.1532018520694; Thu, 19 Jul 2018 09:42:00 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:ab0:21c7:0:0:0:0:0 with HTTP; Thu, 19 Jul 2018 09:42:00 -0700 (PDT) In-Reply-To: <20180719151640.GA24997@duynguyen.home> References: <20180718225110.17639-1-newren@gmail.com> <20180719054424.GB23884@sigill.intra.peff.net> <20180719151640.GA24997@duynguyen.home> From: Elijah Newren Date: Thu, 19 Jul 2018 09:42:00 -0700 Message-ID: Subject: Re: 2.18.0 Regression: packing performance and effectiveness To: Duy Nguyen Cc: Git Mailing List , Jeff King Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Jul 19, 2018 at 8:16 AM, Duy Nguyen wrote: > On Thu, Jul 19, 2018 at 07:57:37AM +0200, Duy Nguyen wrote: >> I thought 2M was generous but I was obviously wrong. I'd like to see >> the biggest delta size in this pack and whether it's still reasonable >> to increase OE_DELTA_SIZE_BITS. But if it's very close to 4GB limit >> then we could just store 64-bit delta size in a separate array. > > I realize now that these two options don't have to be mutually > exclusive and I should provide a good fallback in terms of performance > anyway. > > So Elijah, could you try this patch and see if performance and pack > size go back to 1.7.0? I can write proper commit message and test > support later if it proves a good improvement. Thanks for the quick turnaround. Unfortunately, I have some bad news. With this patch, I get the following: $ /usr/bin/time -f 'MaxRSS:%M Time:%e' git gc --aggressive Enumerating objects: 4460703, done. Counting objects: 100% (4460703/4460703), done. Delta compression using up to 40 threads. Compressing objects: 100% (3807140/3807140), done. Writing objects: 100% (4460703/4460703), done. Total 4460703 (delta 2831383), reused 1587071 (delta 0) error: failed to unpack compressed delta at offset 183854150 from .git/objects/pack/pack-30d4f0b0e5a03dc91a658a0586f4e74cdf4a94d6.pack fatal: packed object 20ce811e53dabbb8ef9368c108cbbdfa65639c03 (stored in .git/objects/pack/pack-30d4f0b0e5a03dc91a658a0586f4e74cdf4a94d6.pack) is corrupt error: failed to run prune MaxRSS:40025196 Time:2531.52 It looks like this comes after it deleted the old packs, so running git fsck afterwards prints lots of errors. Just in case they're helpful at all, there are 26 "error: failed to unpack compressed delta at offset..." messages, 26 "error: cannot unpack ... from ... at offset ..." messages, 17 "error: failed to read delta base object..." messages, 7 "broken link from ... to ..." messages, four missing blobs, and three missing trees. (This was run on a copy of the repo, so no harm done; I can still use the original.) > -- 8< -- > diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c > index ebc8cefb53..7f3546057d 100644 > --- a/builtin/pack-objects.c > +++ b/builtin/pack-objects.c > @@ -2023,10 +2023,6 @@ static int try_delta(struct unpacked *trg, struct unpacked *src, > delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size); > if (!delta_buf) > return 0; > - if (delta_size >= (1U << OE_DELTA_SIZE_BITS)) { > - free(delta_buf); > - return 0; > - } > > if (DELTA(trg_entry)) { > /* Prefer only shallower same-sized deltas. */ > diff --git a/pack-objects.c b/pack-objects.c > index 92708522e7..191ed45faf 100644 > --- a/pack-objects.c > +++ b/pack-objects.c > @@ -160,6 +160,8 @@ struct object_entry *packlist_alloc(struct packing_data *pdata, > > if (!pdata->in_pack_by_idx) > REALLOC_ARRAY(pdata->in_pack, pdata->nr_alloc); > + if (pdata->delta_size) > + REALLOC_ARRAY(pdata->delta_size, pdata->nr_alloc); > } > > new_entry = pdata->objects + pdata->nr_objects++; > @@ -177,3 +179,17 @@ struct object_entry *packlist_alloc(struct packing_data *pdata, > > return new_entry; > } > + > +void oe_prepare_delta_size_array(struct packing_data *pack) > +{ > + int i; > + > + /* > + * nr_alloc, not nr_objects to align with realloc() strategy in > + * packlist_alloc() > + */ > + ALLOC_ARRAY(pack->delta_size, pack->nr_alloc); > + > + for (i = 0; i < pack->nr_objects; i++) > + pack->delta_size[i] = pack->objects[i].delta_size_; > +} > diff --git a/pack-objects.h b/pack-objects.h > index edf74dabdd..978500e474 100644 > --- a/pack-objects.h > +++ b/pack-objects.h > @@ -14,7 +14,7 @@ > * above this limit. Don't lower it too much. > */ > #define OE_SIZE_BITS 31 > -#define OE_DELTA_SIZE_BITS 20 > +#define OE_DELTA_SIZE_BITS 21 > > /* > * State flags for depth-first search used for analyzing delta cycles. > @@ -93,7 +93,6 @@ struct object_entry { > * uses the same base as me > */ > unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */ > - unsigned delta_size_valid:1; > unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */ > unsigned z_delta_size:OE_Z_DELTA_BITS; > unsigned type_valid:1; > @@ -130,6 +129,7 @@ struct packing_data { > uint32_t index_size; > > unsigned int *in_pack_pos; > + unsigned long *delta_size; > > /* > * Only one of these can be non-NULL and they have different > @@ -330,20 +330,27 @@ static inline void oe_set_size(struct packing_data *pack, > static inline unsigned long oe_delta_size(struct packing_data *pack, > const struct object_entry *e) > { > - if (e->delta_size_valid) > + if (!pack->delta_size) > return e->delta_size_; > - return oe_size(pack, e); > + return pack->delta_size[e - pack->objects]; > } > > +void oe_prepare_delta_size_array(struct packing_data *pack); > static inline void oe_set_delta_size(struct packing_data *pack, > struct object_entry *e, > unsigned long size) > { > e->delta_size_ = size; > - e->delta_size_valid = e->delta_size_ == size; > - if (!e->delta_size_valid && size != oe_size(pack, e)) > - BUG("this can only happen in check_object() " > - "where delta size is the same as entry size"); > + if (!pack->delta_size && e->delta_size_ == size) > + return; > + /* > + * We have had at least one delta size exceeding OE_DELTA_SIZE_BITS > + * limit. delta_size_ will not be used anymore. All delta sizes are now > + * from the delta_size[] array. > + */ > + if (!pack->delta_size) > + oe_prepare_delta_size_array(pack); > + pack->delta_size[e - pack->objects] = size; > } > > #endif > -- 8< -- > > > -- > Duy