Hi all, By mapping the WAL files by each backend in to its address
space using "mmap" system call , there will be bigimprovements in performance from the following point of view:
1. Each backend directly writes in to the address
space which is obtained by maping the WAL files. this saves the write system call at the end
of
every transaction which transfres 8k of data from user space to kernel. 2. since
everytransaction does not modify all the 8k
content of WAL page , so by issuing the fsync , the kernel only transfers only the
kernel pages which are modified , which is 4k for linux so fsync time is saved by twice.
Any comments ?.
Regards
jana