Hello Robert,
I think our concerns are roughly classified into two:
(1) Performance
(2) Consistency
And your "different concern" is rather into (2), I think.
I'm also worried about it, but I have no good answer for now. I suppose mmap(flags|=MAP_SHARED) called by multiple
backendprocesses for the same file works consistently for both PMEM and non-PMEM devices. However, I have not found
anyevidence such as specification documents yet.
I also made a tiny program calling memcpy() and msync() on the same mmap()-ed file but mutually distinct address range
inparallel, and found that there was no corrupted data. However, that result does not ensure any consistency I'm
worriedabout. I could give it up if there *were* corrupted data...
So I will go to (1) first. I will test the way Heikki told us to answer whether the cost of mmap() and munmap() per
WALsegment, etc, is reasonable or not. If it really is, then I will go to (2).
Best regards,
Takashi
--
Takashi Menjo <takashi.menjou.vg@hco.ntt.co.jp>
NTT Software Innovation Center