Re: shared_buffers vs Linux file cache

Thanks very much, Glyn, Jeff, and Tom. That was very clearly explained.

A related case, see the following top dump. The Postgres process is using
87g residential memory, which I thought was the physical memory consumed by
a process that can't be shared with others. While, the free+cached is about
155gb. But, (87 + 155) is bigger than the total available 198g RAM. Does
this mean some of the residential memory used by Postgres is actually
shareable to others?

>> Mem: 198311880k total, 183836408k used, 14475472k free, 8388k buffers
>> Swap: 4194300k total, 314284k used, 3880016k free, 141105408k cached
>>
>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
>> 15338 postgres 20 0 97.9g 87g 87g S 0.3 46.4 21:47.44
>> postgres: checkpointer process
>> 27473 postgres 20 0 98.1g 29g 29g S 0.0 15.8 2:14.93
>> postgres: xxxx idle
>> 4710 postgres 20 0 98.1g 24g 23g S 0.0 12.7 1:17.41
>> postgres: xxxx idle

>> 26587 postgres 20 0 98.0g 15g 15g S 0.0 8.0 1:21.24

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