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linux-signed-lowlatency-hwe-6.5 package

  1. Bug #2051733
  2. Comment #7

Comment 7 for bug 2051733

Revision history for this message
Lastique (andysem) wrote : Re: Specifying nohz_full disables CPU frequency scaling

I have run a quick `7z b` benchmark on the lowlatency kernel with and without `nohz_full` parameter, and the results are fairly close:

No `nohz_full` parameter:

                       Compressing | Decompressing
Dict Speed Usage R/U Rating | Speed Usage R/U Rating
         KiB/s % MIPS MIPS | KiB/s % MIPS MIPS

22: 82694 1333 6033 80445 | 741767 1584 3994 63265
23: 81022 1400 5896 82552 | 736593 1589 4011 63731
24: 79427 1429 5978 85401 | 722675 1581 4011 63433
25: 77665 1459 6077 88676 | 711778 1587 3990 63346
---------------------------------- | ------------------------------
Avr: 1405 5996 84269 | 1585 4002 63444
Tot: 1495 4999 73856

With `nohz_full=1-15` parameter:

                       Compressing | Decompressing
Dict Speed Usage R/U Rating | Speed Usage R/U Rating
         KiB/s % MIPS MIPS | KiB/s % MIPS MIPS

22: 84475 1357 6055 82177 | 738578 1552 4060 62993
23: 80361 1376 5951 81878 | 726439 1482 4240 62852
24: 80275 1437 6006 86312 | 715778 1496 4199 62827
25: 77007 1448 6073 87924 | 708632 1563 4034 63066
---------------------------------- | ------------------------------
Avr: 1404 6021 84573 | 1523 4133 62935
Tot: 1464 5077 73754

In the latter case, decompressing is slightly slower, but definitely not "800MHz" slower, so it looks like the problem is indeed with frequency reporting rather than scaling.