Roger Espel Llima <[EMAIL PROTECTED]> writes:
> On Tue, Sep 19, 2000 at 03:24:50PM -0400, Joe Schaefer wrote:
> > On linux, the ext2 filesystem is VERY efficient at buffering filesystem
> > writes (see http://www.tux.org/lkml/#s9-12). If the post data is small
> > ( I don't know what the default size is, but the FILE buffer for the tmpfile
> > is adjustable with setvbuf) it's never written to disk. AFAIK, the only
> > problem with this arrangement for small posts is the extra file descriptor
> > consumed by the apache process.
>
> Yeah, I know it's fairly negligible, but I'm not sure the FILE buffer is
> the one that matters here. If I fwrite(), rewind() and then fread()
> again, AFAIK libc's stdio still translates this into real kernel
> write(), lseek(), read() [strace woudl be the final judge here]. From
> there, the kernel can be smart enough to not actually even touch the
> disk, but that doesn't work with e.g journaling filesystems which impose
> stronger sequential conditions on disk writes, or systems like BSD that
> do synchronous metadata updates. And in any case, you're still doing
> extra memory copies to and from kernel space.
>
> If it was hard to do it otherwise i'd agree with you, but it sounds so
> simple to keep it in a memory buffer when it's under 16k or some similar
> limit, that I just think it's much more "obviously right" to do it that
> way.
Sounds good- thanks for the details. How about making a lower limit
(for switching from a memory buffer to tmpfile) configurable?
Any thoughts on what the directive should be called?
--
Joe Schaefer
[EMAIL PROTECTED]
SunStar Systems, Inc.
