Hello Heikki, > I have the same comments on this that I had on the previous patch, see: > > https://www.postgresql.org/message-id/2aec6e2a-6a32-0c39-e4e2-aad854543aa8%40iki.fi
Thanks. I re-read your messages [1][2]. What you meant, AFAIU, is how about using memory-mapped WAL segment files as WAL buffers, and switching CPU instructions or msync() depending on whether the segment files are on PMEM or not, to sync inserted WAL records. It sounds reasonable, but I'm sorry that I haven't tested such a program yet. I'll try it to compare with my non-volatile WAL buffer. For now, I'm a little worried about the overhead of mmap()/munmap() for each WAL segment file. You also told a SIGBUS problem of memory-mapped I/O. I think it's true for reading from bad memory blocks, as you mentioned, and also true for writing to such blocks [3]. Handling SIGBUS properly or working around it is future work. Best regards, Takashi [1] https://www.postgresql.org/message-id/83eafbfd-d9c5-6623-2423-7cab1be3888c%40iki.fi [2] https://www.postgresql.org/message-id/2aec6e2a-6a32-0c39-e4e2-aad854543aa8%40iki.fi [3] https://pmem.io/2018/11/26/bad-blocks.htm -- Takashi Menjo <takashi.menjou...@hco.ntt.co.jp> NTT Software Innovation Center
