Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait

From: Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz)
Date: Thu Feb 08 2001 - 11:11:26 EST


> > The problem is that aio_read and aio_write are pretty useless for ftp or
> > http server. You need aio_open.
>
> Could you explain this?

If the server is sending many small files, disk spends huge amount time
walking directory tree and seeking to inodes. Maybe opening the file is
even slower than reading it - read is usually sequential but open needs to
seek at few areas of disk.

And if you have one-threaded server using open, close, aio_read and
aio_write, you actually block the whole server while it is opening a
single file. This is not how async io is supposed to work.

Mikulas

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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:11 EST