nocache makes MC very slow

birdie-github commented 4 years ago

First, MC takes at least a few seconds to start.

Then, every directory change takes half a second.

I've no idea why it's happening.

pavlinux commented 4 years ago

It doesn’t work for me at all :)


$ env NOCACHE_FLUSHALL=1 NOCACHE_NR_FADVISE=2 nocache mc && cachestats -v  /usr/bin/mc;

pages in cache: 253/253 (100.0%)  [filesize=1012.0K, pagesize=4K]

cache map:
     0: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
    32: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
    64: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
    96: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
   128: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
   160: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
   192: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|
   224: |x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|x|`

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Feh commented 4 years ago

In general the expectation of actively working to get rid of a file system cache would indeed be to slow an application down if it repeatedly accesses the file.

If you care about MC being fast when called under nocache, could you describe what the binary is doing? (E.g. summarize an strace of a typical slow action.)

Feh / nocache

nocache makes MC very slow #39