Fwd: Workspace overflow handling

[Martin Blix Grydeland]

Forgot reply-all

Martin

---------- Forwarded message ----------
From: Martin Blix Grydeland <martin at varnish-software.com>
Date: 10 February 2015 at 09:48
Subject: Re: Workspace overflow handling
To: Poul-Henning Kamp <phk at phk.freebsd.dk>



On 9 February 2015 at 22:20, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> --------
>
> I've spent a lot of time pondering this over the years, and as
> always with hard problems, there are no easy, cheap and correct
> solutions,
>

I'd say two out of three still isn't bad, and in my opinion the proposal
scores good on both the easy and cheap metric, presenting a feasible
solution although maybe interim. I believe this could be achieved within
reasonable time frame and be a 95% solution to a problem that I feel is
becoming increasingly urgent to fix.


> I don't belive much in your "just double the allocation with unused
> VM" idea, first because there is no guarantee that the number two
> is magic and big enough, so we'd still have to check all over the
> place, and second because the necessay management of map/unmap is
> a needless complication.
>

I believe that for the core Varnish code some minimum amount of workspace
needed to succeed could be calculated (some number of headers we know we
could set multiplied with the maximum header length, and add the overhead
of the IO vectors...) As long as WS size is much larger than this, it will
work. And then it'll buy us the time we need to do it the correct way.


>
> So summary:  I think we all agree on the end result, and I belive
> that mark/report is our main means to get there, but there is
> so much code to hack and so little time...
>

Which is really the basis for this pragmatic approach to the problem.

Martin

-- 
<http://varnish-software.com>*Martin Blix Grydeland*
Senior Developer | Varnish Software AS
Mobile: +47 992 74 756
We Make Websites Fly!



-- 
<http://varnish-software.com>*Martin Blix Grydeland*
Senior Developer | Varnish Software AS
Mobile: +47 992 74 756
We Make Websites Fly!
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