Thread

1. FEATURE REQUEST: Role vCPU limit/priority

   Yoni Sade <yonisade83@gmail.com> — 2024-01-21T18:07:42Z

   It would be useful to have the ability to define for a role default vCPU
   affinity limits/thread priority settings so that more active sessions could
   coexist similar to MySQL resource groups
   <https://dev.mysql.com/doc/refman/8.0/en/resource-groups.html>.
   
   Best Regards,
   Yoni Sade
   

2. Re: FEATURE REQUEST: Role vCPU limit/priority

   Aleksander Alekseev <aleksander@timescale.com> — 2024-01-22T10:43:45Z

   Hi Yoni,
   
   > It would be useful to have the ability to define for a role default vCPU affinity limits/thread priority settings so that more active sessions could coexist similar to MySQL resource groups.
   
   To me this sounds like a valuable feature.
   
   Would you be interested in working on it? Typically it is a good idea
   to start with an RFC document and discuss it with the community.
   
   -- 
   Best regards,
   Aleksander Alekseev
   
   
   
   

3. Re: FEATURE REQUEST: Role vCPU limit/priority

   Yoni Sade <yonisade83@gmail.com> — 2024-01-23T11:57:32Z

   Well, I'm not a developer, I just wanted to pitch this idea as a DBA who
   would make use of this feature.
   
   Best Regards,
   Yoni Sade
   
   ‫בתאריך יום ב׳, 22 בינו׳ 2024 ב-12:43 מאת ‪Aleksander Alekseev‬‏ <‪
   aleksander@timescale.com‬‏>:‬
   
   > Hi Yoni,
   >
   > > It would be useful to have the ability to define for a role default vCPU
   > affinity limits/thread priority settings so that more active sessions could
   > coexist similar to MySQL resource groups.
   >
   > To me this sounds like a valuable feature.
   >
   > Would you be interested in working on it? Typically it is a good idea
   > to start with an RFC document and discuss it with the community.
   >
   > --
   > Best regards,
   > Aleksander Alekseev
   >
   

4. Re: FEATURE REQUEST: Role vCPU limit/priority

   shammat@gmx.net — 2024-01-23T12:09:22Z

   Yoni Sade schrieb am 21.01.2024 um 19:07:
   > It would be useful to have the ability to define for a role default
   > vCPU affinity limits/thread priority settings so that more active
   > sessions could coexist similar to MySQL resource groups
   > <https://dev.mysql.com/doc/refman/8.0/en/resource-groups.html>.
   
   To a certain extent, you can achieve something like that using Linux cgroups
   
   https://www.cybertec-postgresql.com/en/linux-cgroups-for-postgresql/
   
   
   
   
   
   

5. Re: FEATURE REQUEST: Role vCPU limit/priority

   Aleksander Alekseev <aleksander@timescale.com> — 2024-01-23T13:10:40Z

   Hi,
   
   > Well, I'm not a developer, I just wanted to pitch this idea as a DBA who would make use of this feature.
   
   I don't think one shouldn't be a developer in order to write an RFC
   and drive its discussion within the community. On top of that I'm
   pretty confident as a DBA you can contribute tests and documentation.
   
   -- 
   Best regards,
   Aleksander Alekseev
   
   
   
   

6. Re: FEATURE REQUEST: Role vCPU limit/priority

   Andres Freund <andres@anarazel.de> — 2024-01-23T18:10:27Z

   Hi,
   
   On 2024-01-23 13:09:22 +0100, Thomas Kellerer wrote:
   > Yoni Sade schrieb am 21.01.2024 um 19:07:
   > > It would be useful to have the ability to define for a role default
   > > vCPU affinity limits/thread priority settings so that more active
   > > sessions could coexist similar to MySQL resource groups
   > > <https://dev.mysql.com/doc/refman/8.0/en/resource-groups.html>.
   > 
   > To a certain extent, you can achieve something like that using Linux cgroups
   > 
   > https://www.cybertec-postgresql.com/en/linux-cgroups-for-postgresql/
   
   If you do that naively, you just run into priority inversion issues. E.g. a
   backend holding a critical lwlock not getting scheduled for a while because it
   exceeded it CPU allocation, preventing higher priority processes from
   progressing.
   
   I doubt you can implement this in a robust manner outside of postgres.
   
   Regards,
   
   Andres
   
   
   
   

7. Re: FEATURE REQUEST: Role vCPU limit/priority

   Bruce Momjian <bruce@momjian.us> — 2024-01-23T18:25:04Z

   On Tue, Jan 23, 2024 at 10:10:27AM -0800, Andres Freund wrote:
   > Hi,
   > 
   > On 2024-01-23 13:09:22 +0100, Thomas Kellerer wrote:
   > > Yoni Sade schrieb am 21.01.2024 um 19:07:
   > > > It would be useful to have the ability to define for a role default
   > > > vCPU affinity limits/thread priority settings so that more active
   > > > sessions could coexist similar to MySQL resource groups
   > > > <https://dev.mysql.com/doc/refman/8.0/en/resource-groups.html>.
   > > 
   > > To a certain extent, you can achieve something like that using Linux cgroups
   > > 
   > > https://www.cybertec-postgresql.com/en/linux-cgroups-for-postgresql/
   > 
   > If you do that naively, you just run into priority inversion issues. E.g. a
   > backend holding a critical lwlock not getting scheduled for a while because it
   > exceeded it CPU allocation, preventing higher priority processes from
   > progressing.
   > 
   > I doubt you can implement this in a robust manner outside of postgres.
   
   FYI, here is an article about priority inversion:
   
   	https://www.geeksforgeeks.org/priority-inversion-what-the-heck/
   
   -- 
     Bruce Momjian  <bruce@momjian.us>        https://momjian.us
     EDB                                      https://enterprisedb.com
   
     Only you can decide what is important to you.