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. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html