# Add support for setting worker processes and CPU affinity automatically **URL:** \ **Category:** NGINX\ **Created:** [January 12, 2012, 4:38pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681 "2012-01-12T16:38:01Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [January 12, 2012, 4:38pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/1 "2012-01-12T16:38:01Z")
Hi, It’s a little bit inconvenient to set the CPU affinities with many-core-system. For example, to fully utilize a 16-core Linux box, we have to write something like this: worker\_processes 16; worker\_cpu\_affinity 1000000000000000 0100000000000000 0010000000000000 0001000000000000 0000100000000000 0000010000000000 0000001000000000 0000000100000000 0000000010000000 0000000001000000 0000000000100000 0000000000010000 0000000000001000 0000000000000100 0000000000000010 0000000000000001; This patch will make life much easier: worker\_processes auto; worker\_cpu\_affinity auto; Please see the attachment for more detail. Regards, ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 12, 2012, 5:07pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/2 "2012-01-12T17:07:39Z")
Hi Joshua, nice work indeed, thanks! Do you have a practical example when such explicit binding does better work than OS scheduler? – Maxim K. +7 (910) 4293178 > **[Advanced Load Balancer, Web Server, & Reverse Proxy - NGINX](https://www.nginx.com/)** > > NGINX accelerates content and application delivery, improves security, and facilitates availability and scalability for the busiest websites on the Internet. ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 12, 2012, 5:42pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/3 "2012-01-12T17:42:22Z")
Hi Maxim, On Fri, Jan 13, 2012 at 12:07 AM, Maxim K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > [http://nginx.com/](http://nginx.com/) Thanks! Actually we did a test against the CPU affinity feature before and found it was a little bit better than what the OS scheduler did, not too much though. This is as expected since there will be less CPU cache missing with this feature turned on. Regards, ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 12, 2012, 6:54pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/4 "2012-01-12T18:54:49Z")
On Thursday 12 January 2012 19:37:15 Joshua Z. wrote: > This patch will make life much easier: > worker\_processes auto; > worker\_cpu\_affinity auto; > > Please see the attachment for more detail. You use “ngx\_ncpu” global variable and for Linux you set it by sysconf(\_SC\_NPROCESSORS\_ONLN). On freeBSD and MacOS systems it set by sysctls(hw.ncpu), and it is equal to 1 on others. Which means that your “auto” settings are very inaccurate. Sometimes the “worker\_processes” directive will be equal to 2 \* cores or more, sometimes it will be equal to 1, and if you’re lucky, then it will be equal to real CPU cores. So, I don’t think that this patch makes life easier. In fact, it creates a false sense of optimal worker\_processes setting. Even if ngx\_ncpu would be always equal to real hardware cores number, it wouldn’t be optimal for every use cases. wbr, Valentin V. Bartenev ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 11:15am UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/5 "2012-01-13T11:15:43Z")
> Setting CPU affinity is available on Linux systems only. Please > correct me if I’m wrong. That’s wrong. Just some start points: FreeBSD: cpuset\_setaffinity(2) Solaris: probably better to start from processor\_bind(2) man page. HP/UP: pset\_bind(2), psrset(1m) AIX: bindprocessor() Sure other systems with more or less advances \*MP support have a similar functionality. – Maxim K. +7 (910) 4293178 > **[F5 NGINX: Built for cloud-native apps. Ready for AI traffic.](https://www.f5.com/products/nginx)** > > Deliver modern applications with NGINX. Explore high-performance load balancing, API gateways, and web server solutions trusted by top global enterprises. ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 11:28am UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/6 "2012-01-13T11:28:06Z")
Hi, > > Setting CPU affinity is available on Linux systems only. Please > > correct me if I’m wrong. > > That’s wrong. I believe that Joshua meant that workers CPU affinity _in nginx_ works only on Linux right now (which is true). Best regards, Piotr S. \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) \> ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 11:04am UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/7 "2012-01-13T11:04:35Z")
Hi, On Fri, Jan 13, 2012 at 1:53 AM, Valentin V. Bartenev [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On Thursday 12 January 2012 19:37:15 Joshua Z. wrote: [snip] Thank you very much for the review. You use “ngx\_ncpu” global variable and for Linux you set it by > sysconf(\_SC\_NPROCESSORS\_ONLN). > > On freeBSD and MacOS systems it set by sysctls(hw.ncpu), and it is equal > to 1 on others. Setting CPU affinity is available on Linux systems only. Please correct me if I’m wrong. > Which means that your “auto” settings are very inaccurate. Sometimes the > “worker\_processes” directive will be equal to 2 \* cores or more, sometimes > it will be equal to 1, and if you’re lucky, then it will be equal to real > CPU cores. This is mostly caused by the hyper-threading feature of some CPUs. I don’t think this is an issue if hyper-threading is turned on. Sure we need to find a better way to detect the number of CPUs on a system. > So, I don’t think that this patch makes life easier. In fact, it creates a > false sense of optimal worker\_processes setting. Even if ngx\_ncpu would be > always equal to real hardware cores number, it wouldn’t be optimal for > every > use cases. It’s not ‘optimal’, but ‘automatic’. This patch still supports setting worker processes and CPU affinities mannually as what the standard Nginx does 😉 Regards, ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 11:34am UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/8 "2012-01-13T11:34:19Z")
On Friday 13 January 2012 14:04:11 Joshua Z. wrote: > > sysconf(\_SC\_NPROCESSORS\_ONLN). > > > > On freeBSD and MacOS systems it set by sysctls(hw.ncpu), and it is equal > > to 1 on others. > > Setting CPU affinity is available on Linux systems only. Please correct me > if I’m wrong. You’re right. But I generally said about “ngx\_ncpu”, that also affects “auto” setting in your patch for the “worker\_processes” directive. > > Which means that your “auto” settings are very inaccurate. Sometimes the > > “worker\_processes” directive will be equal to 2 \* cores or more, > > sometimes it will be equal to 1, and if you’re lucky, then it will be > > equal to real CPU cores. > > This is mostly caused by the hyper-threading feature of some CPUs. I don’t > think this is an issue if hyper-threading is turned on. Sure we need to > find a better way to detect the number of CPUs on a system. Yeap, we need to find a better way. And I don’t think the solution will be simple and it is worth to be implemented in a web server. > > So, I don’t think that this patch makes life easier. In fact, it creates > > a false sense of optimal worker\_processes setting. Even if ngx\_ncpu > > would be always equal to real hardware cores number, it wouldn’t be > > optimal for every > > use cases. > > It’s not ‘optimal’, but ‘automatic’. This patch still supports setting > worker processes and CPU affinities mannually as what the standard Nginx > does 😉 So, when you need some automation for configuration and deployment, the better solution would be using proper software for that task, isn’t it? Like Puppet, for example. wbr, Valentin V. Bartenev ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 2:19pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/9 "2012-01-13T14:19:17Z")
On 1/13/12 2:27 PM, Piotr S. wrote: > Hi, > > > > Setting CPU affinity is available on Linux systems only. Please > > > correct me if I’m wrong. > > > > That’s wrong. > > I believe that Joshua meant that workers CPU affinity _in nginx_ > works only on Linux right now (which is true). Ah, I see, thanks. I just wonder how useful this option in real environment. – Maxim K. +7 (910) 4293178 > **[F5 NGINX: Built for cloud-native apps. Ready for AI traffic.](https://www.f5.com/products/nginx)** > > Deliver modern applications with NGINX. Explore high-performance load balancing, API gateways, and web server solutions trusted by top global enterprises. ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 2:08pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/10 "2012-01-13T14:08:45Z")
Hi, On Fri, Jan 13, 2012 at 6:33 PM, Valentin V. Bartenev [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On Friday 13 January 2012 14:04:11 Joshua Z. wrote: [snip] > So, when you need some automation for configuration and deployment, the > better > solution would be using proper software for that task, isn’t it? Like > Puppet, > for example. OK. If this patch would not be accepted, could you please also review the first one? Thank you. Regards, ---
**Author:** ![Joshua\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ccd318/32.png) [@Joshua\_Z](https://www.ruby-forum.com/u/Joshua_Z)\ **Post date:** [January 13, 2012, 3:07pm UTC](https://www.ruby-forum.com/t/add-support-for-setting-worker-processes-and-cpu-affinity-automatically/215681/11 "2012-01-13T15:07:04Z")
Hello! On Fri, Jan 13, 2012 at 09:08:25PM +0800, Joshua Z. wrote: > > So, when you need some automation for configuration and deployment, the > > better > > solution would be using proper software for that task, isn’t it? Like > > Puppet, > > for example. > > OK. > If this patch would not be accepted, I wouldn’t say it won’t be accepted at all, I think we need something like this, but probably not by default. > could you please also review the first one? I’m currently looking into it. Maxim D.