4 ms·

> Some program executables are multiple megabytes in size these days I have shared the figures from my system right now in my earlier comment. The memory requi

• laumars 8y ago
  But that’s what you’re storing in the system memory, not CPU cache. Ok let’s say the kernel does cache recently accessed memeory in the L2 cache, you’re still competing with everything else - particularly in a multi-user or multi-threaded system. So that is not going to stay in L2 for long. You’re making so many assumptions about the host platform and they simply don’t stack up for the majority of cases - it’s just that most systems are fast enough to hide your incorrect assumptions. Also your understanding of how file system caching works is completely off. Granted that’s not something most normal engineers need to worry about, but given the claims you’re making about nnn, I would suggest you spend a little time researching the fundamentals here. Edit: > I am happy we had a very informative discussion towards the end. This is what I expected from the other dev That was exactly what the other dev was doing. You just weren’t ready to listen to him - which is why I started making comments about your “narky” replies. ;)
  • apjana 8y ago
    Well, I shared the numbers, I gave you ways to test it. We are done here.
    • laumars 8y ago
      but You’re not proving that the data you are expecting to be in L2 actually ends up in L2. Let alone persists long enough to be recalled from L2 when you do your rescans. Your test is crude and thus doesn’t prove anything. Which is what we have all been telling you right from the start!!!! You cannot just throw numbers up and say “look I’m right” if the test of flawed from the outset. But yes, it’s probably better we do call it a day.
      • apjana 8y ago
        I expected you would run the test. Anyway, here's the data and it aligns with my expectation and figures. ## Fired `nnn` in my home dir. - all cached, no major page faults ~$ /usr/bin/time -v nnn Command being timed: "nnn" User time (seconds): 0.00 System time (seconds): 0.00 Percent of CPU this job got: 0% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:03.77 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 3400 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 274 Voluntary context switches: 6 Involuntary context switches: 1 Swaps: 0 File system inputs: 0 File system outputs: 0 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 ~$ ## Fired `nnn` on an external disk root in du mode, went into a subdir, came back to root. - no major page faults - File system inputs: 14680 - 220 KB cached extra ~$ /usr/bin/time -v nnn -S /media/vaio/49462fdf-010c-40cc-89db-ef125e7dae99/tmp/ Command being timed: "nnn -S /media/vaio/49462fdf-010c-40cc-89db-ef125e7dae99/tmp/" User time (seconds): 0.02 System time (seconds): 0.27 Percent of CPU this job got: 3% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:08.30 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 3620 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 337 Voluntary context switches: 576 Involuntary context switches: 2 Swaps: 0 File system inputs: 14680 File system outputs: 0 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 ~$ ## Fired `nnn` again (around 2 mins later, I was formatting the above text) on the external disk root in du mode. - File system inputs: 0 ** So even between 2 distinct instances of nnn, _all_ the data fetched in the first instance remained cached. ~$ /usr/bin/time -v nnn -S /media/vaio/49462fdf-010c-40cc-89db-ef125e7dae99/tmp/ Command being timed: "nnn -S /media/vaio/49462fdf-010c-40cc-89db-ef125e7dae99/tmp/" User time (seconds): 0.00 System time (seconds): 0.01 Percent of CPU this job got: 0% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.31 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 3616 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 329 Voluntary context switches: 5 Involuntary context switches: 0 Swaps: 0 File system inputs: 0 File system outputs: 0 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 ~$