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Re: Anyone else sees a bootstrap failure (Linux-x86)?
- From: Andrew Haley <aph at redhat dot com>
- To: "Ranjit Mathew" <rmathew at hotmail dot com>
- Cc: java at gcc dot gnu dot org
- Date: Tue, 21 Oct 2003 14:30:46 +0100
- Subject: Re: Anyone else sees a bootstrap failure (Linux-x86)?
- References: <BAY1-F30XTdoifHqw8p0000f778@hotmail.com>
Ranjit Mathew writes:
> > > On Solaris 8, I did see an improvement with "-pipe", but it
> > > was always a ~5% improvement.
> >
> >This is surprising. You don't say what filesystem you were using.
>
> It's UFS without journalling, AFAICT.
>
> But I still don't fully comprehend why "-pipe" cannot be faster -
> at some point in time, the OS's filesystem buffers will get full
> and will have to be flushed out to the disc, incurring I/O
> penalties, during "normal" compilation.
It depends on how the /tmp filesystem behaves. It can be designed so
that the creation, use, and subsequent deletion of a temporary file
never results in any I/O activity at all.
> If the compiler outputs assembly code in one large burst (or a few
> large bursts) and the assembler reads its input in one large burst
> (or a few large bursts), the interlocking effect in "-pipe" that
> you talked about wouldn't be so pronounced.
Right, but the cost of creating, reading, and writing a file in /tmp
is also (or should be, at least) very small.
> It's not very black and white to me still.
Me neither. At least on a well-designed OS we know the effect should
be very small. 5% seems to me rather a lot. Something to do with
Solaris, perhaps.
Andrew.