Re: Is sendfile all that sexy?

[Linus Torvalds]

In article <[e-mail]>,
Albert D. Cahalan <[e-mail]> wrote:
>Ingo Molnar writes:
>> On Mon, 15 Jan 2001, Jonathan Thackray wrote:
>
>>> It's a very useful system call and makes file serving much more
>>> scalable, and I'm glad that most Un*xes now have support for it
>>> (Linux, FreeBSD, HP-UX, AIX, Tru64). The next cool feature to add to
>>> Linux is sendpath(), which does the open() before the sendfile() all
>>> combined into one system call.
>
>Ingo Molnar's data in a nice table:
>
>open/close  7.5756 microseconds
>stat        5.4864 microseconds
>write       0.9614 microseconds
>read        1.1420 microseconds
>syscall     0.6349 microseconds
>
>Rather than combining open() with sendfile(), it could be combined
>with stat().

Note that "fstat()" is fairly low-overhead (unlike "stat()" it obviously
doesn't have to parse the name again), so "open+fstat" is quite fine
as-is. 

		Linus