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SubjectRe: Linux 2.4.20-SMP: where is all my CPU time going?
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> > TIMESTAMP [2002] CLIENT NAME             RUN-TIME         SYS-TIME
> > Sep 22 23:08:00: SETI-5 20606.560000 190.480000
>
> incidentally, what's the meaning of the client-name column?
> (no, I've never run seti, so don't know whether it increments
> through spurious client names on the same machine for some reason...)

My super demon program has 6 "client" directories, each of which
contains an instance of the setiathome program. The super demon keeps
two of these clients processing work units at any one time; 2 because
the machine has 2 CPUs.

> > > do you have any other data? if the kernel happens to pull pages away
> > > from the seti process, it could easily cause this sort of thing.
> >
> > Well, I actually have no idea what sort of activity counts towards the
> > sys-time total. Is this time spent in spinlocks? Semaphores? Waiting
> > for DMA transfers to complete? And we're talking 36 minutes-worth of
> > sys-time here! It sounds as if some in-kernel process is going
> > completely off the deep end.
>
> you have absolutely no data to support that. all you know is that for some
> reason, the kernel thinks seti is taking up more in-kernel time. in general,
> driver-level stuff (like irq's and dma) is not accounted by the kernel,
> and thus shows up in the user-time of whatever process happens to be running.
>
> do you have *elapsed* time per workunit? that's actually a hard number,
> not a wishywashy one like user/sys times. if there's an increase in
> elapsed time, the phenomenon is a little more interesting.

Yes I do. The work-unit began on Feb 08 2003 17:30:35 and finished
on Feb 09 2003 12:22:21. That's approximately 19 hours of wall time,
of which there were 32747.76 seconds of user time and 3840.99 seconds
of sys time. Compare this to a previous work unit which began on Feb
07 2003 16:16:48, finished on Feb 08 2003 02:27:32 (10 hours of wall
time) and took 33207.24 and 219.95 seconds of user and sys time
respectively. This is where my "9 hours of missing run-time" assertion
comes from.

> > > check your cron jobs; I'm guessing you simply run updatedb or something
> > > at that interval. it does enough IO to flush pages in the seti client's
> > > working set.
> >
> > My only cron job is one that runs "rmmod -a" every hour.
>
> really? no logwatch, logrotate, tmpclean, updatedb, tripwire,
> preen-man-pages?

Nope. This is a home-built box.

> > Could cache-thrashing account for the 9 hours of missing run-time? I
>
> sure. you have basically no useful data, since user/sys time accounting
> is purely for amusement purposes, not taken seriously by the kernel.

Terrific.

> the only way you can possibly track this down is by getting more data
> around one of these spikes. something like running vmstat periodically,
> as well as grabbing /proc/{meminfo,slabinfo}. perhaps kernel profiling
> or oprofile during non-spike and spike times.

Well on the assumption that I'm still in a spike time, here's some
more memory info.

$ cat /proc/meminfo
total: used: free: shared: buffers: cached:
Mem: 1058336768 860172288 198164480 0 59092992 614592512
Swap: 509956096 12288000 497668096
MemTotal: 1033532 kB
MemFree: 193520 kB
MemShared: 0 kB
Buffers: 57708 kB
Cached: 598712 kB
SwapCached: 1476 kB
Active: 342780 kB
Inactive: 414884 kB
HighTotal: 130944 kB
HighFree: 2044 kB
LowTotal: 902588 kB
LowFree: 191476 kB
SwapTotal: 498004 kB
SwapFree: 486004 kB

$ cat /proc/slabinfo
slabinfo - version: 1.1 (SMP)
kmem_cache 80 80 244 5 5 1 : 252 126
uhci_urb_priv 1 63 60 1 1 1 : 252 126
fib6_nodes 226 226 32 2 2 1 : 252 126
ip6_dst_cache 60 60 192 3 3 1 : 252 126
ndisc_cache 60 60 128 2 2 1 : 252 126
nfs_write_data 147 209 352 17 19 1 : 124 62
nfs_read_data 0 0 352 0 0 1 : 124 62
nfs_page 188 440 96 7 11 1 : 252 126
hpsb_packet 0 0 100 0 0 1 : 252 126
tcp_tw_bucket 60 60 128 2 2 1 : 252 126
tcp_bind_bucket 273 339 32 3 3 1 : 252 126
tcp_open_request 80 80 96 2 2 1 : 252 126
inet_peer_cache 59 59 64 1 1 1 : 252 126
ip_fib_hash 10 113 32 1 1 1 : 252 126
ip_dst_cache 192 192 160 8 8 1 : 252 126
arp_cache 30 30 128 1 1 1 : 252 126
blkdev_requests 512 520 96 13 13 1 : 252 126
devfsd_event 169 169 20 1 1 1 : 252 126
journal_head 324 702 48 8 9 1 : 252 126
revoke_table 1 253 12 1 1 1 : 252 126
revoke_record 226 226 32 2 2 1 : 252 126
dnotify_cache 0 0 20 0 0 1 : 252 126
file_lock_cache 120 120 96 3 3 1 : 252 126
fasync_cache 3 202 16 1 1 1 : 252 126
uid_cache 3 113 32 1 1 1 : 252 126
skbuff_head_cache 522 648 160 22 27 1 : 252 126
sock 192 192 928 48 48 1 : 124 62
sigqueue 164 290 132 6 10 1 : 252 126
kiobuf 0 0 64 0 0 1 : 252 126
cdev_cache 273 295 64 5 5 1 : 252 126
bdev_cache 10 118 64 2 2 1 : 252 126
mnt_cache 18 177 64 3 3 1 : 252 126
inode_cache 26053 28416 480 3269 3552 1 : 124 62
dentry_cache 41382 43650 128 1455 1455 1 : 252 126
dquot 3 60 128 2 2 1 : 252 126
filp 1144 1200 128 40 40 1 : 252 126
names_cache 38 38 4096 38 38 1 : 60 30
buffer_head 158790 211920 96 5172 5298 1 : 252 126
mm_struct 312 312 160 13 13 1 : 252 126
vm_area_struct 1838 2360 96 59 59 1 : 252 126
fs_cache 354 354 64 6 6 1 : 252 126
files_cache 189 189 416 21 21 1 : 124 62
signal_act 132 132 1312 44 44 1 : 60 30
size-131072(DMA) 0 0 131072 0 0 32 : 0 0
size-131072 0 0 131072 0 0 32 : 0 0
size-65536(DMA) 0 0 65536 0 0 16 : 0 0
size-65536 0 0 65536 0 0 16 : 0 0
size-32768(DMA) 0 0 32768 0 0 8 : 0 0
size-32768 0 0 32768 0 0 8 : 0 0
size-16384(DMA) 0 0 16384 0 0 4 : 0 0
size-16384 2 13 16384 2 13 4 : 0 0
size-8192(DMA) 0 0 8192 0 0 2 : 0 0
size-8192 4 18 8192 4 18 2 : 0 0
size-4096(DMA) 0 0 4096 0 0 1 : 60 30
size-4096 112 142 4096 112 142 1 : 60 30
size-2048(DMA) 0 0 2048 0 0 1 : 60 30
size-2048 130 190 2048 76 95 1 : 60 30
size-1024(DMA) 0 0 1024 0 0 1 : 124 62
size-1024 288 288 1024 72 72 1 : 124 62
size-512(DMA) 0 0 512 0 0 1 : 124 62
size-512 330 392 512 49 49 1 : 124 62
size-256(DMA) 0 0 256 0 0 1 : 252 126
size-256 264 390 256 26 26 1 : 252 126
size-128(DMA) 2 30 128 1 1 1 : 252 126
size-128 2088 2970 128 99 99 1 : 252 126
size-64(DMA) 0 0 64 0 0 1 : 252 126
size-64 1119 1475 64 24 25 1 : 252 126
size-32(DMA) 2 113 32 1 1 1 : 252 126
size-32 8679 11413 32 88 101 1 : 252 126

$ vmstat 5
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
2 0 12000 192384 57708 598728 0 0 3 3 3 4 94 6 0 0
2 0 12000 192384 57708 598728 0 0 0 6 101 186 99 1 0 0
2 0 12000 192376 57708 598728 0 0 0 6 101 186 100 0 0 0
2 0 12000 193272 57708 598728 0 0 0 0 100 185 99 1 0 0
2 0 12000 194432 57708 598728 0 0 0 0 100 180 99 1 0 0
3 0 12000 193404 57708 598728 0 0 0 0 100 180 99 1 0 0
2 0 12000 194432 57708 598728 0 0 0 0 100 179 99 1 0 0
3 0 12000 194432 57708 598728 0 0 0 17 104 177 99 1 0 0
2 0 12000 193144 57708 598728 0 0 0 0 100 185 98 2 0 0
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