Robert E. Bruccoleri wrote: > Dear Tom, > Thank you for the explanation. I did not understand what was > going on in lwlock.c.
Yes, as Tom said, using the pre-7.2 code on SMP machines, if one backend had a spinlock, the other backend would TAS loop trying to get the lock until its timeslice ended or the other backend released the lock. Now, we TAS, then sleep on a semaphore and get woken up when the first backend releases the lock. We worked hard on that logic, I can tell you that and it was a huge discussion topic on the Fall of 2001. > My systems are all SGI Origins having between 8 and 32 > processors, and I've been running PostgreSQL on them for about 5 > years. These machines do provide a number of good mechanisms for high > performance shared memory parallelism that I don't think are found > elsewhere. I wish that I had the time to understand and tune > PostgreSQL to run really well on them. > I have a question for you and other developers with regard to > my SGI needs. If I made a functional Origin 2000 system available to > you with hardware support, would the group be willing to tailor the > SGI port for better performance? We would have to understand how the SGI code is better than our existing code on SMP machines. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
