Re: [PATCH] dtrace probes for memory manager

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com>
Cc: Bernd Helmle <mailings(at)oopsware(dot)de>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCH] dtrace probes for memory manager
Date: 2009-12-11 18:12:27
Message-ID: 603c8f070912111012w6e9b38cejeaa809acb7aa7a06@mail.gmail.com
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On Fri, Dec 11, 2009 at 1:04 PM, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
> We know that performance impact is less then 1% probably less then 0.6%.
> The question is if it is acceptable or not. I personally think that it
> is acceptable. However if not, I will start work on backup solution with
> dtraced AllocSet and some switching mechanism. But it needs little
> discussion about design. And first we need decision about current
> performance impact.

As far as I am concerned that is way too much, particularly
considering that your test case isn't designed to be particularly
memory-allocation intensive, and if it is up to me I will reject this.
Even a quarter-percent slowdown for a feature that will be used only
by a small fraction of users only a small fraction of time time seems
totally unacceptable to me.

...Robert

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