Re: disk-based fds in select/poll

[Alan Cox]

> I am thinking that a read() (or sendfile()) that would block because the
> pages aren't in core should instead post a request for the pages to be
> loaded (some kind of readahead mecanism?) and return immediately (maybe
> having given some data that *was* in core). A subsequent read() could

reads posts a readahead anyway so streaming reads tend not to block much

> SGI's AIO might be a solution here, does it use threads? I'm trying to
> avoid context switching as much as possible, to keep the CPU cache as
> warm as possible.

glibc 2.2 does thread based aio_ and it will tend to avoid cache damage as
the thread share the mm but on SMP its quite possible the read wil occur on
the other CPU. Of course kernel based I/O might do the same too..