From: Linus Torvalds <torvalds@osdl.org>
To: Junio C Hamano <junkio@cox.net>
Cc: Nicolas Pitre <nico@cam.org>, git@vger.kernel.org
Subject: Re: [PATCH] diff-delta: bound hash list length to avoid O(m*n) behavior
Date: Fri, 3 Mar 2006 22:21:43 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0603032217470.22647@g5.osdl.org> (raw)
In-Reply-To: <7vfylzx7t3.fsf@assigned-by-dhcp.cox.net>
On Fri, 3 Mar 2006, Junio C Hamano wrote:
>
> The first round. The set of objects packed were from
> today's Linus tip (everything down to epoch v2.6.12-rc2), 193309
> objects in total, on my Duron 750 with slow disks.
>
> real user sys bytes savings
> master 11m17.121s 10m23.280s 0m47.290s 109045599 N/A
> nico 25m37.058s 23m0.770s 2m20.460s 104401392 4.25%
> jc 24m12.072s 21m45.120s 2m16.400s 104409761 4.25%
Ouch.
Btw, it's often worth using /usr/bin/time instead of the bash built-in
time. Why? Because /usr/bin/time reports one absolutely _hugely_ important
number (maybe more important than almost any of the other numbers in
there).
Which one? It's the "minor pagefaults". That's a very good approximation
of memory usage overhead.
We've already had one person report that they ran out of memory when
packing. So memory usage is actually a problem.
Anyway, it looks like the 16-byte window is the way to go, even regardless
of any memory use issue.
Linus
next prev parent reply other threads:[~2006-03-04 6:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-28 4:09 [PATCH] diff-delta: bound hash list length to avoid O(m*n) behavior Nicolas Pitre
2006-02-28 6:51 ` Junio C Hamano
2006-02-28 8:10 ` Junio C Hamano
2006-02-28 17:05 ` Nicolas Pitre
2006-03-01 10:38 ` Junio C Hamano
2006-03-01 17:22 ` Nicolas Pitre
2006-03-04 2:28 ` Junio C Hamano
2006-03-04 2:39 ` Junio C Hamano
2006-03-04 3:01 ` Nicolas Pitre
2006-03-04 6:21 ` Linus Torvalds [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-03-08 19:32 Nicolas Pitre
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