Re: mmap() versus read()
Richard Gooch (rgooch@atnf.CSIRO.AU)
Mon, 9 Mar 1998 13:08:11 +1100
Dean Gaudet writes:
>
>
> On Mon, 9 Mar 1998, Richard Gooch wrote:
>
> > The syscall overhead is peanuts. It's more like 10 000 times faster
> > than a disc seek. The syscall overhead is simply not worth
> > considering.
>
> It's 10k times faster sure if you *have to go to disk*. What happens when
> I build a 512Mb web server with only 256Mb of active content? Suddenly
> I'm paying for per-request syscalls I don't need. I know, it's all about
> trade-offs :)
>
> I could show you a beautiful trace of apache 1.3 hacked up a bit in which
> it served 75 requests in something like 20 system calls. This means there
> are no per-request syscalls required currently... There's a few
> connection setup and teardown calls, and the rest were writev()s or
> write()s -- the client was http/1.1 pipelining, so I'm "cheating"... but
> pipelining clients are here already and 6 months to a year from now they
> should be common.
How long does it take to service and complete a transaction, assuming
all data is in RAM?
Regards,
Richard....
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