Hi all, In Linux exists the ionice(1) for "get/set program io scheduling class and priority". In FreeBSD we've nice(1), renice(8) and even rtprio, idprio(1) but if I'm understanding correctly, they're related to CPU priorty only, not to I/O. ?Is there some ionice(1) equivalent in FreeBSD? -- I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain. Bene Gesserit Litany Against Fear.
Jordi Espasa Clofent wrote:> ?Is there some ionice(1) equivalent in FreeBSD?No. - Andrew
On Wed, 3 Feb 2010, Jordi Espasa Clofent wrote:> In Linux exists the ionice(1) for "get/set program io scheduling > class and priority". > > In FreeBSD we've nice(1), renice(8) and even rtprio, idprio(1) but if > I'm understanding correctly, they're related to CPU priorty only, not > to I/O. > > ?Is there some ionice(1) equivalent in FreeBSD?There is no IO scheduler in FreeBSD outside of some experimental patches at http://unix.derkeiler.com/Mailing-Lists/FreeBSD/stable/2009-01/msg00316.html (I have no idea of their status) -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 188 bytes Desc: This is a digitally signed message part. Url : http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20100203/b55c05e9/attachment.pgp
On 02/02/2010 17:19, Jordi Espasa Clofent wrote:> > In FreeBSD we've nice(1), renice(8) and even rtprio, idprio(1) but if > I'm understanding correctly, they're related to CPU priorty only, not > to I/O.That's not entirely true. A thread's CPU priority is still going to affect its ability to be scheduled on the CPU, and if it's waiting in the read() or write() syscalls, then this will make a difference to how quickly it can complete the next call. However, it doesn't explicitly affect relative I/O prioritization. This is another story entirely. I suspect in a lot of cases adding a weight to per thread I/O, isn't going to make much difference for disk I/Os which are being sorted for the geometry (e.g. AHCI NCQ). So I guess my question is, 'why do you need I/O scheduling, and what aspect of system performance are you trying to solve with it' ?