Hi Matty,
Kernel async I/O just works on RAW devices at the moment.
Kernel async I/O give a small incremental improvement, but only in the
order of a few percent in optimal cases. The user-land thread
emulation works quite well when direct I/O is enabled (without it, the
single writer lock will
Howdy,
Does anyone know why kernel asynchronous I/O is limited to raw devices? Is
it possible to extend kaio to the file system layer? Would there be any
benefit? Is there a noticeable performance difference between the userland
and kernel asynchronous I/O implemenation when UFS is used with l
10, 2005 9:49 PM
Subject: [perf-discuss] Kernel Asynchronous I/O
Howdy,
Does anyone know why kernel asynchronous I/O is limited to raw devices? Is
it possible to extend kaio to the file system layer? Would there be any
benefit? Is there a noticeable performance difference between the use
Regarding benefits of having kernel async I/O support for filesytems,
I would think it should certainly be better from performance point.
Also having all of async I/O in the kernel would mean we don't have
to have the libaio implementation in the user land which is
unnecessarily complicated.
Si
That is because the filesystem framework (VFS/VNODE)
and the filesystems do not implement an async I/O interface.
This requires that the relevant modules (filesystems) implement
the necessary I/O queuing and notification mechanism for
async I/O requests.
The kernel async I/O is currently imple
Howdy,
Does anyone know why kernel asynchronous I/O is limited to raw devices? Is
it possible to extend kaio to the file system layer? Would there be any
benefit? Is there a noticeable performance difference between the userland
and kernel asynchronous I/O implementation when UFS is used with la
