On Tue, Sep 14, 1999 at 04:40:37PM -0400, Christopher Sedore wrote: > > > On Mon, 13 Sep 1999, Jayson Nordwick wrote: > > > While reading through (at least trying to... I wish there was some sort of > > kernel documentation available, the entry fee is very high) the aio_* calls, > > I had a few questions to clear up my understanding: > > > > 1) Do they only work on files? The only implementation I see is in > > the VFS layer. > > Any read()/write()'able descriptor should work. > > > 2) It is my understanding that it uses an aio daemon running as a kernel > > thread (the aio_daemon() call kind of give that one away). It seems as > > if this can be almost entirely done in user space. More important to what > > I am trying to do, it seems as if aio_* does not give peak latency > > or throughput performace, since the aio_daemon has to compete for resources > > along with all other processes. > > > > Should aio_* be used for applications that have high performance > > requirements? What does aio_* get you above having a seperate > > thread pumping in/out data? > > The aio_* stuff (I use a custom patched version in 4.x) offers performance > advantages over select() with large numbers of descriptors. In terms of > efficiency, I don't have any trouble saturating full-duplex 100mbit link > with aio routines on a reasonably fast box (PII-400 512MB). > > As more work gets done to the aio stuff, there are some potential early > advantages available to multiprocessor machines (since the program > 'driving' the aio could run concurrently with the kernel code moving > network or disk data). > > -Chris
Do you by any change have an idea how to fix PR kern/13075 (signal is not posted for async I/O on raw devices) Thanks, -- Ruslan Ermilov Sysadmin and DBA of the r...@ucb.crimea.ua United Commercial Bank, r...@freebsd.org FreeBSD committer, +380.652.247.647 Simferopol, Ukraine http://www.FreeBSD.org The Power To Serve http://www.oracle.com Enabling The Information Age To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
