From: Jeff King <peff@peff.net>
To: Stefan Beller <sbeller@google.com>
Cc: "git@vger.kernel.org" <git@vger.kernel.org>
Subject: Re: [PATCH 2/2] use zstd zlib wrapper
Date: Wed, 14 Sep 2016 23:28:46 -0700 [thread overview]
Message-ID: <20160915062845.sfackmnezb7oy3j5@sigill.intra.peff.net> (raw)
In-Reply-To: <CAGZ79kYcB-x40_w1fcWL3NSp8JU9SPrTAEiru-6Jpb7fDM1Y0w@mail.gmail.com>
On Wed, Sep 14, 2016 at 06:22:17PM -0700, Stefan Beller wrote:
> > Disappointingly, the answer seems to be "no".
>
> After having looked at the data, I disagree with the conclusion.
> And for that I think we need to reason about the frequency
> of the operations happening.
I definitely agree that reads outnumber writes, and it's OK to have an
asymmetric tradeoff between the two. zstd5 isn't _too_ bad in that
respect. I guess I was just disappointed that the pack size was still
bigger, as I was really hoping to see some speed tradeoff without
getting a worse pack.
The other thing to weigh against is "if we were designing it today"
versus "is it worth the compatibility headaches now". A 6% improvement
in "rev-list --objects" is not that amazing for a data format change.
Bitmaps were an _easier_ data format change and are more like a 99%
speedup.
They do not apply to every operations, but we may be able to do similar
space/time tradeoffs that are easier to handle in terms of backwards
compatibility, and which yield bigger results.
-Peff
next prev parent reply other threads:[~2016-09-15 6:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-14 23:55 Journal of Failed Git Experiments, Volume 1 Jeff King
2016-09-14 23:56 ` [PATCH 1/2] obj_hash: convert to a critbit tree Jeff King
2016-09-15 0:52 ` Stefan Beller
2016-09-15 1:13 ` Jeff King
2016-09-14 23:58 ` [PATCH 2/2] use zstd zlib wrapper Jeff King
2016-09-15 1:22 ` Stefan Beller
2016-09-15 6:28 ` Jeff King [this message]
2016-09-25 14:17 ` Journal of Failed Git Experiments, Volume 1 Johannes Schindelin
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