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From: Duy Nguyen <pclouds@gmail.com>
To: Elijah Newren <newren@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>, Jeff King <peff@peff.net>
Subject: Re: [PATCH] pack-objects: fix performance issues on packing large deltas
Date: Sun, 22 Jul 2018 08:49:14 +0200	[thread overview]
Message-ID: <CACsJy8AdyhdSu1LaER4J+wg03nT_i_pfc29Jxp8acTOS+7EXWw@mail.gmail.com> (raw)
In-Reply-To: <CABPp-BHecS-TewK=tCxEZkCiM_QF=Pj3LkDWOT6+2F1VCu-KcQ@mail.gmail.com>

On Sun, Jul 22, 2018 at 8:22 AM Elijah Newren <newren@gmail.com> wrote:
>
> On Fri, Jul 20, 2018 at 9:47 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> > On Fri, Jul 20, 2018 at 10:43:25AM -0700, Elijah Newren wrote:
> >> Out of curiosity, would it be possible to use the delta_size_ field
> >> for deltas that are small enough, and only use an external data
> >> structure (perhaps a hash rather than an array) for the few deltas
> >> that are large?
> >
> > We could. And because repack time is still a bit higher in your
> > linux.git case. Let's try this. No locking in common case and very
> > small locked region when we hit large deltas
>
> This one looks like a winner.  Labelling this as fix-v7, this rounds
> out the table to:
>
> Version  Time (s)
> -------  --------
>  2.17.0   621.36
>  2.18.0   621.80
>  fix-v5   836.29
>  fix-v6   831.73
>  fix-v2   619.96
>  fix-v7   622.88
>
> So the runtime is basically within the noise of different runs of the
> timing for 2.17.0 or 2.18.0 or -v2, and is much faster than -v5 or
> -v6.

Thanks. I'm looking forward to asking you to test lock-related changes
on this 40-core monster in the future :D

Unrelated point of improvement for the future. I notice that at least
on my machine, i have 100% cpu on one core during writing phase,
likely because deltas are being recomputed to be written down and we
don't produce deltas fast enough. We should be able to take advantage
of multiple cores to recompute deltas in advance at this stage and
shorten pack-objects time some more.
-- 
Duy

  reply	other threads:[~2018-07-22  6:49 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18 22:51 2.18.0 Regression: packing performance and effectiveness Elijah Newren
2018-07-18 22:51 ` [RFC PATCH] fix-v1: revert "pack-objects: shrink delta_size field in struct object_entry" Elijah Newren
2018-07-18 22:51 ` [RFC PATCH] fix-v2: make OE_DELTA_SIZE_BITS a bit bigger Elijah Newren
2018-07-19  5:41 ` 2.18.0 Regression: packing performance and effectiveness Duy Nguyen
2018-07-19  5:49   ` Jeff King
2018-07-19 15:27   ` Elijah Newren
2018-07-19 15:43     ` Duy Nguyen
2018-07-19  5:44 ` Jeff King
2018-07-19  5:57   ` Duy Nguyen
2018-07-19 15:16     ` Duy Nguyen
2018-07-19 16:42       ` Elijah Newren
2018-07-19 17:23         ` Jeff King
2018-07-19 17:31           ` Duy Nguyen
2018-07-19 18:24             ` Duy Nguyen
2018-07-19 19:17               ` Jeff King
2018-07-19 23:11               ` Elijah Newren
2018-07-20  5:28                 ` Jeff King
2018-07-20  5:30                   ` Jeff King
2018-07-20  5:47                   ` Duy Nguyen
2018-07-20 17:21                   ` Elijah Newren
2018-07-19 17:04       ` Jeff King
2018-07-19 19:25       ` Junio C Hamano
2018-07-19 19:27         ` Junio C Hamano
2018-07-20 15:39 ` [PATCH] pack-objects: fix performance issues on packing large deltas Nguyễn Thái Ngọc Duy
2018-07-20 17:40   ` Jeff King
2018-07-21  4:23     ` Duy Nguyen
2018-07-23 21:37       ` Jeff King
2018-07-20 17:43   ` Elijah Newren
2018-07-20 23:52     ` Elijah Newren
2018-07-21  4:07       ` Duy Nguyen
2018-07-21  7:08         ` Duy Nguyen
2018-07-21  4:47     ` Duy Nguyen
2018-07-21  6:56       ` Elijah Newren
2018-07-21  7:14         ` Duy Nguyen
2018-07-22  6:22       ` Elijah Newren
2018-07-22  6:49         ` Duy Nguyen [this message]
2018-07-23 12:34     ` Elijah Newren
2018-07-23 15:50       ` Duy Nguyen
2018-07-22  8:04   ` [PATCH v2] " Nguyễn Thái Ngọc Duy
2018-07-23 18:04     ` Junio C Hamano
2018-07-23 18:38       ` Duy Nguyen
2018-07-23 18:49         ` Duy Nguyen
2018-07-23 21:30           ` Jeff King
2018-07-26  8:12     ` Johannes Sixt

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