High load on interrupts
Hi!
On Arrakis, one of my m68k buildds, I discovered recently that "top" shows a
quite high activity doing hardware interrupts:
top - 13:57:09 up 1 day, 21:52, 3 users, load average: 0.10, 0.07, 0.01
Tasks: 69 total, 1 running, 68 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.6% us, 0.0% sy, 0.0% ni, 0.0% id, 0.0% wa, 99.4% hi, 0.0% si
Mem: 127340k total, 116048k used, 11292k free, 28372k buffers
Swap: 272192k total, 19532k used, 252660k free, 47608k cached
This 99.4% hi seems to be something like an idle process counter as it drops
relative to CPU usage:
Cpu(s): 2.5% us, 0.0% sy, 68.1% ni, 0.0% id, 0.0% wa, 29.4% hi, 0.0% si
(vivaldi, another 060 m68k buildd)
"vmstat 3" reports:
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 1 19528 10144 28468 48024 0 0 12 21 192 34 55 45 0 0
0 0 19528 10084 28468 48024 0 0 0 0 424 23 1 99 0 0
0 0 19528 10084 28472 48024 0 0 0 11 415 26 6 94 0 0
0 0 19528 10084 28472 48024 0 0 0 0 408 20 0 100 0 0
0 0 19528 10084 28476 48024 0 0 0 4 410 21 0 100 0 0
So, roughly 400 interrups per timeframe.
Whereas on my PPC and i386 system:
PPC:
top - 14:04:13 up 10 days, 18:30, 5 users, load average: 0.00, 0.09, 0.08
Cpu(s): 0.9% us, 0.3% sy, 0.0% ni, 98.3% id, 0.1% wa, 0.2% hi, 0.2% si
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 0 86412 36496 20 138348 0 0 0 0 29 301 0 0 99 0
0 0 86412 36496 20 138348 0 0 0 0 41 376 1 1 98 0
0 0 86412 36496 20 138348 0 0 0 0 33 328 1 2 97 0
0 0 86412 36496 20 138348 0 0 0 4 21 269 1 1 98 0
i386:
top - 14:11:32 up 49 days, 16:28, 9 users, load average: 0.03, 0.04, 0.00
Cpu(s): 3.3% us, 1.5% sy, 0.0% ni, 94.7% id, 0.0% wa, 0.1% hi, 0.5% si
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 19976 6952 28 228936 0 0 3 0 7 9 3 1 95 0
0 0 19976 6952 28 228936 0 0 0 0 287 401 4 1 95 0
0 0 19976 6952 28 228936 0 0 0 6 285 404 4 3 93 0
0 0 19976 6920 28 228940 0 0 0 9 350 431 5 5 90 0
1 0 19976 6920 28 228940 0 0 0 5 319 417 5 4 91 0
As you can see, on both systems the "hi" percentage is nearly 0%, whereas it
is approx. 99% on my idle m68k.
A "watch -d cat /proc/interrupts" shows that the most active interrupt
handles are timer, CIAB, CIAA and fb vertb handler.
Nothing strange with that, but I wonder if something is broken in m68k
kernel that makes it reporting such a high "hi" percentage?
Kernels are:
Linux arrakis 2.6.12-1-amiga #1 Sat Aug 13 22:59:59 CEST 2005 m68k GNU/Linux
Linux vivaldi 2.6.14-m68k-amiga #10 Thu Dec 1 21:40:17 CET 2005 m68k GNU/Linux
(vivaldi is using Kars' kernel with SCSI patches, arrakis is using a stock
Debian kernel package).
--
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