Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Did we ever come to a conclusion about excessive SMP context switching > > under load? > > Yeah: it's bad. > > Oh, you wanted a fix? That seems harder :-(. AFAICS we need a redesign > that causes less load on the BufMgrLock. However, the traditional > solution to too-much-contention-for-a-lock is to break up the locked > data structure into finer-grained units, which means *more* lock > operations in total. Normally you expect that the finer-grained lock > units will mean less contention. But given that the issue here seems to > be trading physical ownership of the lock's cache line back and forth, > I'm afraid that the traditional approach would actually make things > worse. The SMP issue seems to be not with whether there is > instantaneous contention for the locked datastructure, but with the cost > of making it possible for processor B to acquire a lock recently held by > processor A.
I see. I don't even see a TODO in there. :-( -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
