Subject: Re: [Fwd: [linux-audio-dev] info point on linux hdr]
From: Stephen C. Tweedie (sct_AT_redhat.com)
Date: Tue Apr 18 2000 - 16:43:38 EEST
Hi,
On Mon, Apr 17, 2000 at 01:05:12PM -0400, Paul Barton-Davis wrote:
>
> Acknowledging your much greater wisdom in this are than me, I don't
> understand the above given that, in my experience:
>
> 1) pre-allocation takes a *long* time. Allocating 24 203MB files on a
> clean ext2 partition of 18GB takes many, many minutes, for example.
> Presumably, the same overhead is being incurred when block
> allocation happens "on the fly".
It is not the allocation which is taking ages, it's the actual
writing of the data. Even if you preallocate, you still have the
data writes to worry about! Preallocation just can't gain that
much. (It can gain some, but not as much as you would like.)
> 2) Why am I not having any of these problems ? Unlike Benno's code, I
> have a working application that runs just fine.
Umm, you are running a different application on different hardware, and
you are wondering why you don't see the same effects... not surprising!
In particular, it's really the use of multiple streams which causes big
problems. The difference between SCSI and IDE is also significant.
(That difference is hopefully improvede by the elevator patches.)
--Stephen
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