Bruce Momjian <pgman@candle.pha.pa.us> wrote: > > > > Here is a small patch to prevent undesired WAL file caching by kernel. > > > > posix_fadvise(POSIX_FADV_DONTNEED) attempts to free cached pages and > > > > the kernel will discard them in preference to other data caches. > > > > > > On plenty of platforms, this won't even compile ... > > Yes, but we probably have to have a configure test to see if > posix_fadvise exists too. I will keep this for 8.2.
I think we can use _POSIX_ADVISORY_INFO to test if posix_fadvise exists. Also, I added the check on whether WAL archiving is enabled, because archivers might use the caches to read the WAL segment. By the way, should we put posix_fadvise on the separated place with renaming pg_fadvise? If we use posix_fadvise in other purposes, for example, read-ahead control, the separation would be good to keep codes clean. --- ITAGAKI Takahiro NTT Cyber Space Laboratories
xlog-with-fadvise.patch
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