Re: so much clock interrupts?!
On Sat, Nov 26, 2005 at 10:27:42PM -0500, Chuck Swiger wrote: >> I'm also wondering wether 1000 Hz on a Soekris net4801 (Geode 266 MHz) >> won't be overkill. I'm planning to migrate some of them from 5.4 to 6.0, >> and doubting wether to change the new default to its more conservative >> previous setting of 100 Hz. > > For what it's worth, I have kern.hz="200" in /boot/loader.conf on an > EPIA-M6000 running 6.0-STABLE... Ah, good hint. I'm running 6.0-STABLE with its default hz=1000 on a generic EPIA 5000 board and everything still runs smootly there. > -Chuck Thanks, -cpghost. -- Cordula's Web. http://www.cordula.ws/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
cpghost wrote: On Fri, Nov 25, 2005 at 07:45:03AM +0100, Markus Trippelsdorf wrote: Yes, I guess it increases performance on a high throughput webserver or router that uses polling. But on the Desktop it only increases the overhead without any benefits at all. 2000 interrupts per second per core for the timer is a ridiculous high number and I reduce it simply for aesthetic reasons. The default settings try to give a 1-millisecond timing granularity, which seems to work pretty well on Pentium-grade and above hardware. Desktop tasks now include soft realtime work like displaying video clips, and obviously realtime 3D games benefit from it HZ=1000. I'm also wondering wether 1000 Hz on a Soekris net4801 (Geode 266 MHz) won't be overkill. I'm planning to migrate some of them from 5.4 to 6.0, and doubting wether to change the new default to its more conservative previous setting of 100 Hz. For what it's worth, I have kern.hz="200" in /boot/loader.conf on an EPIA-M6000 running 6.0-STABLE... -- -Chuck ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Friday 25 November 2005 06:45, Markus Trippelsdorf wrote: > 2000 interrupts per second per core for the timer is a > ridiculous high number and I reduce it simply for aesthetic reasons. > This may be a religious issue and everyone should use what he or she > seems fitting. If you think in a wider perspective, and consider the number of cpu cycles per interrupt on historical and embedded cpus, 2000 Hz is pretty conservative. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
I'm also wondering wether 1000 Hz on a Soekris net4801 (Geode 266 MHz) won't be overkill. I'm planning to migrate some of them from 5.4 to 6.0, probably not. my 400Mhz PII works almost as fast with HZ=1000 and HZ=100 - tested today and doubting wether to change the new default to its more conservative previous setting of 100 Hz. This may be a religious issue and everyone should use what he or she seems fitting. On slow CPUs, it may not be merely a religious issue. :) Markus -cpghost. -- Cordula's Web. http://www.cordula.ws/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]" ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Fri, Nov 25, 2005 at 07:45:03AM +0100, Markus Trippelsdorf wrote: > Yes, I guess it increases performance on a high throughput webserver or > router that uses polling. > But on the Desktop it only increases the overhead without any benefits > at all. 2000 interrupts per second per core for the timer is a > ridiculous high number and I reduce it simply for aesthetic reasons. I'm also wondering wether 1000 Hz on a Soekris net4801 (Geode 266 MHz) won't be overkill. I'm planning to migrate some of them from 5.4 to 6.0, and doubting wether to change the new default to its more conservative previous setting of 100 Hz. > This may be a religious issue and everyone should use what he or she > seems fitting. On slow CPUs, it may not be merely a religious issue. :) > Markus -cpghost. -- Cordula's Web. http://www.cordula.ws/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Fri, Nov 25, 2005 at 07:45:03AM +0100, Markus Trippelsdorf wrote: > On Thu, Nov 24, 2005 at 03:43:59PM -0500, Kris Kennaway wrote: > > On Thu, Nov 24, 2005 at 07:40:40AM +, Markus Trippelsdorf wrote: > > > On 2005-11-24, Wojciech Puchar <[EMAIL PROTECTED]> wrote: > > > > that's what i see in systat with FreeBSD 6.0/i386-SMP > > > > > > > > > > > >540 534 99 pdwak 2000 > > > > cpu0: time > > > > 16825 pdpgs 2000 > > > > cpu1: time > > > > > > > > > > > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second > > > > > > > > isn't it too much?! > > > > > > Yes it is. > > > That's why I have kern.hz="100" in my /boot/loader.conf . > > > > Have you been able to measure a performance benefit from reducing it? > > Have you shown that reducing it does not cause your performance to > > *drop*? It was increased for a reason..it actually increases > > performance on some workloads. > > > Yes, I guess it increases performance on a high throughput webserver or > router that uses polling. > But on the Desktop it only increases the overhead without any benefits > at all. 2000 interrupts per second per core for the timer is a > ridiculous high number and I reduce it simply for aesthetic reasons. > This may be a religious issue and everyone should use what he or she > seems fitting. You should do what makes you feel happy, of course :) Kris pgppTX8JneGWV.pgp Description: PGP signature
Re: so much clock interrupts?!
On Thu, Nov 24, 2005 at 03:43:59PM -0500, Kris Kennaway wrote: > On Thu, Nov 24, 2005 at 07:40:40AM +, Markus Trippelsdorf wrote: > > On 2005-11-24, Wojciech Puchar <[EMAIL PROTECTED]> wrote: > > > that's what i see in systat with FreeBSD 6.0/i386-SMP > > > > > > > > >540 534 99 pdwak 2000 > > > cpu0: time > > > 16825 pdpgs 2000 > > > cpu1: time > > > > > > > > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second > > > > > > isn't it too much?! > > > > Yes it is. > > That's why I have kern.hz="100" in my /boot/loader.conf . > > Have you been able to measure a performance benefit from reducing it? > Have you shown that reducing it does not cause your performance to > *drop*? It was increased for a reason..it actually increases > performance on some workloads. > Yes, I guess it increases performance on a high throughput webserver or router that uses polling. But on the Desktop it only increases the overhead without any benefits at all. 2000 interrupts per second per core for the timer is a ridiculous high number and I reduce it simply for aesthetic reasons. This may be a religious issue and everyone should use what he or she seems fitting. -- Markus ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Fri, Nov 25, 2005 at 01:08:42AM +0100, Wojciech Puchar wrote: > >>That's why I have kern.hz="100" in my /boot/loader.conf . > > > >Have you been able to measure a performance benefit from reducing it? > >Have you shown that reducing it does not cause your performance to > >*drop*? It was increased for a reason..it actually increases > >performance on some workloads. > > > no i'm just asking. > > does hz=1000 means that if i run >1 CPU-bound process per processor it's > switched 1000 times per second between them? or just 1000 times per second > system call is issued that does many system duties, but switches processes > with different frequency? It's used to drive timers and periodic events, including scheduling. Keep in mind that modern computers are roughly 10 times faster than they were a few years ago. Something that runs every 1/100 of a second is actually waiting for 10 times as many CPU cycles as it was on the older machine, which means that it may be working proportionally less efficiently on the new machine. Kris pgpJWmiQ1B74q.pgp Description: PGP signature
Re: so much clock interrupts?!
On Fri, Nov 25, 2005 at 01:09:08AM +0100, Wojciech Puchar wrote: > >>>No, it's just a consequence of HZ=1000 instead of HZ=100. I've > >> > >> > >>so why 2000 not 1000? > >> > >>2000 on each processor! > > > >Technical reasons..anyway, 2000 might look like a large number to you, > >but it's really not unless you're on a very slow machine (like a 486). > > i'm asking why it's 2000, not 1000. I don't remember off-hand. It should be apparent if you look at the code. Kris pgpq8JzZmn4Mx.pgp Description: PGP signature
Re: so much clock interrupts?!
No, it's just a consequence of HZ=1000 instead of HZ=100. I've so why 2000 not 1000? 2000 on each processor! Technical reasons..anyway, 2000 might look like a large number to you, but it's really not unless you're on a very slow machine (like a 486). i'm asking why it's 2000, not 1000. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
That's why I have kern.hz="100" in my /boot/loader.conf . Have you been able to measure a performance benefit from reducing it? Have you shown that reducing it does not cause your performance to *drop*? It was increased for a reason..it actually increases performance on some workloads. no i'm just asking. does hz=1000 means that if i run >1 CPU-bound process per processor it's switched 1000 times per second between them? or just 1000 times per second system call is issued that does many system duties, but switches processes with different frequency? ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Thu, Nov 24, 2005 at 02:05:16PM +0100, Wojciech Puchar wrote: > >> 540 534 99 pdwak 2000 > >> cpu0: > >> time > >>16825 pdpgs 2000 > >>cpu1: > >>time > >> > >> > >>on FreeBSD 5.3 live CD i have 100 not 2000 times per second > >> > >>isn't it too much?! > > > >No, it's just a consequence of HZ=1000 instead of HZ=100. I've > > > so why 2000 not 1000? > > 2000 on each processor! Technical reasons..anyway, 2000 might look like a large number to you, but it's really not unless you're on a very slow machine (like a 486). Kris pgp8NHBaj4sLH.pgp Description: PGP signature
Re: so much clock interrupts?!
On Thu, Nov 24, 2005 at 07:40:40AM +, Markus Trippelsdorf wrote: > On 2005-11-24, Wojciech Puchar <[EMAIL PROTECTED]> wrote: > > that's what i see in systat with FreeBSD 6.0/i386-SMP > > > > > >540 534 99 pdwak 2000 > > cpu0: time > > 16825 pdpgs 2000 > > cpu1: time > > > > > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second > > > > isn't it too much?! > > Yes it is. > That's why I have kern.hz="100" in my /boot/loader.conf . Have you been able to measure a performance benefit from reducing it? Have you shown that reducing it does not cause your performance to *drop*? It was increased for a reason..it actually increases performance on some workloads. Kris pgp8EucOS0n2E.pgp Description: PGP signature
Re: so much clock interrupts?!
On 2005-11-24, Wojciech Puchar <[EMAIL PROTECTED]> wrote: >>> >>> on FreeBSD 5.3 live CD i have 100 not 2000 times per second >>> >>> isn't it too much?! >> >> Yes it is. >> That's why I have kern.hz="100" in my /boot/loader.conf . >> -- > > do you know why they set it too high in 6.0? there must be a reason! Check: http://groups.google.com/group/lucky.freebsd.cvs.all/browse_frm/thread/98c80113071ff35d/c37992b8ceab7de8?tvc=1&q=cvs+commit%3A+src%2Fsys%2Famd64%2Famd64+cpu_switch.S+machdep.c#c37992b8ceab7de8 for a in-depth discussion. -- Markus ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
540 534 99 pdwak 2000 cpu0: time 16825 pdpgs 2000 cpu1: time on FreeBSD 5.3 live CD i have 100 not 2000 times per second isn't it too much?! No, it's just a consequence of HZ=1000 instead of HZ=100. I've so why 2000 not 1000? 2000 on each processor! ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
on FreeBSD 5.3 live CD i have 100 not 2000 times per second isn't it too much?! Yes it is. That's why I have kern.hz="100" in my /boot/loader.conf . -- do you know why they set it too high in 6.0? there must be a reason! ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On 2005-11-24, Wojciech Puchar <[EMAIL PROTECTED]> wrote: > that's what i see in systat with FreeBSD 6.0/i386-SMP > > >540 534 99 pdwak 2000 cpu0: > time > 16825 pdpgs 2000 cpu1: > time > > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second > > isn't it too much?! Yes it is. That's why I have kern.hz="100" in my /boot/loader.conf . -- Markus ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: so much clock interrupts?!
On Thu, Nov 24, 2005 at 01:35:41AM +0100, Wojciech Puchar wrote: > that's what i see in systat with FreeBSD 6.0/i386-SMP > > > 540 534 99 pdwak 2000 cpu0: > time > 16825 pdpgs 2000 cpu1: > time > > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second > > isn't it too much?! No, it's just a consequence of HZ=1000 instead of HZ=100. I've measured this carefully and I can't see it causing a penalty on my workloads. It apparently gives a benefit on machines that do a lot of network I/O. Kris pgpoJ3nS1WLte.pgp Description: PGP signature
so much clock interrupts?!
that's what i see in systat with FreeBSD 6.0/i386-SMP 540 534 99 pdwak 2000 cpu0: time 16825 pdpgs 2000 cpu1: time on FreeBSD 5.3 live CD i have 100 not 2000 times per second isn't it too much?! ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
