[replies sent directly to me may timeout and bounce, since I'm not
online as often as I should be, but I'll check the list archives]
I wrote a while back, in an old freebsd-current list thread, in which it
was determined that WITNESS was to be avoided in -current if one wanted
decent performance...
> Hmmm, a few weeks ago I did some totally unscientific testing, noting
> that -current was much slower than -stable, by playing an mp3 with an
[...]
> explain why FreeBSD's mpg123 takes ~60% CPU and NetBSD's ~30% (vs the
> ~90+% usage by -current)...
> Oh, I'll try rebuilding -current Real Soon^W^W later today, without
> WITNESS, and compare, just to stay on-topic for this list.
And so I did. (build sans WITNESS, not stay on-topic) The results
were, well, interesting.
I built both a WITNESS and a WITNESSless kernel with more recent
k0deZ, and in the case of playing an mp3 file with `mpg123', I
saw practically no difference between the two, based on %cpu as
shown by `top' (like I say, completely unscientific and inaccurate)
That's interesting, because the previous -current+WITNESS reported
a sound-related lock order reversal and mpg123 took >90% cpu, while
neither of the more recent kernels had this lock order reversal.
In fact, the %cpu needed by `mpg123' seemed identical between
-current, both with and without WETNESS, and -stable. Look:
Stable
CPU states: 52.7% user, 0.0% nice, 2.3% system, 5.8% interrupt, 39.2% idle
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
272 beer 45 0 344M 908K RUN 3:10 56.10% 56.10% mpg123-O3
260 root 28 0 1440K 1176K RUN 0:04 0.24% 0.24% top
Current+WITNESS
CPU states: 51.9% user, 0.0% nice, 8.3% system, 12.4% interrupt, 27.4% idle
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
305 beer 115 0 113M 960K RUN 2:06 55.91% 55.91% mpg123-O3
10 root -16 0 0K 12K RUN 1:52 27.39% 27.39% idle
29 root -60 -179 0K 12K WAIT 0:14 5.96% 5.96% irq5: sbc0
12 root -48 -167 0K 12K WAIT 0:07 2.00% 2.00% swi6: tty:sio
313 root 97 0 1544K 1264K RUN 0:02 1.19% 1.17% top
Current-without
CPU states: 54.0% user, 0.0% nice, 6.8% system, 10.6% interrupt, 28.7% idle
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
322 beer 117 0 97400K 1384K RUN 4:44 55.18% 55.18% mpg123-O3
10 root -16 0 0K 12K RUN 5:38 26.95% 26.95% idle
29 root -60 -179 0K 12K WAIT 0:35 6.01% 6.01% irq5: sbc0
12 root -48 -167 0K 12K WAIT 0:19 2.83% 2.83% swi6: tty:sio
313 root 97 0 1544K 1252K RUN 0:16 1.07% 1.07% top
In both -current and -stable, the audio is usually smooth but
periodically has a hiccup or two and loops briefly.
But the very same hardware, booted into NetBSD off the same disk,
running a NetBSD-native binary of mpg123 on NetBSD-current shows this:
CPU states: 38.1% user, 0.0% nice, 1.5% system, 1.0% interrupt, 59.4% idle
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
229 beer 10 0 308K 3828K aud_wr 1:17 37.16% 37.16% mpg123
245 root 28 0 164K 860K CPU 0:00 0.89% 0.29% top
This machine can happily do a second task without it needing to be
`nice'd and still exude clean audio. Not possible with FreeBSD.
Just in case I had botched the optimizations for the FreeBSD versions
of mpg123, I compiled them statically (I couldn't get the NetBSD
version to run under FreeBSD tho), and ran those under NetBSD with
the COMPAT_FREEBSD kernel option. Under FreeBSD I saw no change
in CPU needed, whilst surprisingly, the static FreeBSD binary run
under NetBSD on the same hardware needed *less* cpu than before:
CPU states: 20.3% user, 0.0% nice, 1.0% system, 0.0% interrupt, 78.7% idle
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
241 beer 36 0 512K 2020K RUN 0:24 21.71% 21.63% mpg123-stati
268 root 28 0 164K 860K CPU 0:00 0.74% 0.24% top
I'm concerned. I know this isn't at all scientific, but why would
NetBSD require about 1/3 the CPU to run the same binary as either
-stable or -current FreeBSD on the same hardware? Can I be slowing
my FreeBSD OSen by using a kernel option that I shouldn't, or is
something else coming into play?
Another thing of note, with this hardware, under FreeBSD, it takes
some seconds (ten or so) from the time I start mpg123 until it stops
pegging the CPU and starts to play audio, while with NEtBSD, playing
starts immediately with both binaries. If that means anything.
-stable: ls: /etc/malloc.conf: No such file or directory
-current: /FreeBSD-CURRENT/etc/malloc.conf -> aj
sound card: sbc0: <ESS ES1868> at port 0x220-0x22f,0x388-0x38b,0x330-0x331 irq 5 drq
1,0 on isa0
pcm0: <ESS 18xx DSP> on sbc0
cpu: CPU: Pentium/P54C (75.00-MHz 586-class CPU)
Origin = "GenuineIntel" Id = 0x524 Stepping = 4
Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
real memory = 75497472 (73728K bytes)
(entire dmesg on request if of interest)
kernel config options used, if something is obviously a hog, -stable:
options INET #InterNETworking
options FFS #Berkeley Fast Filesystem
options FFS_ROOT #FFS usable as root device [keep this!]
options SOFTUPDATES #Enable FFS soft updates support
options MFS #Memory Filesystem
options PROCFS #Process filesystem
options COMPAT_43 #Compatible with BSD 4.3 [KEEP THIS!]
options SCSI_DELAY=2000 #Delay (in ms) before probing SCSI
options USERCONFIG #boot -c editor
options VISUAL_USERCONFIG #visual boot -c editor
options KTRACE #ktrace(1) support
options SYSVSHM #SYSV-style shared memory
options SYSVMSG #SYSV-style message queues
options SYSVSEM #SYSV-style semaphores
options P1003_1B #Posix P1003_1B real-time extensions
options _KPOSIX_PRIORITY_SCHEDULING
options ICMP_BANDLIM #Rate limit bad replies
options KBD_INSTALL_CDEV # install a CDEV entry in /dev
options ATA_STATIC_ID #Static device numbering
options PQ_CACHESIZE=512 # color for 512k/16k cache
options CPU_SUSP_HLT
options USER_LDT #allow user-level control of i386 ldt
options SHMMAXPGS=10000 # max amount of shared memory pages (4k on i386)
options SHMALL=8192 # max amount of shared memory (bytes)
options SHMMIN=1 # min shared memory segment size (bytes)
options SHMMNI=200 # max number of shared memory identifiers
options SHMSEG=200 # max shared memory segments per process
options SEMMAP=31 # amount of entries in semaphore map
options SEMMNI=128 # number of semaphore identifiers in the system
options SEMMNS=65536 # number of semaphores in the system
options SEMMNU=31 # number of undo structures in the system
options SEMMSL=512 # max number of semaphores per id
options SEMOPM=101 # max number of operations per semop call
options SEMUME=11 # max number of undo entries per process
options DDB
options DDB_UNATTENDED
options PERFMON
options PPP_BSDCOMP #PPP BSD-compress support
options PPP_DEFLATE #PPP zlib/deflate/gzip support
options PPP_FILTER #enable bpf filtering (needs bpf)
options RANDOM_IP_ID
options ICMP_BANDLIM
options NFS_NOSERVER #Disable the NFS-server code.
options UFS_DIRHASH
options EXT2FS
options CAM_MAX_HIGHPOWER=2
options MSGBUF_SIZE=40960
options PPS_SYNC
options MAXCONS=12 # number of virtual consoles
options SC_DISABLE_REBOOT # disable reboot key sequence
options SC_HISTORY_SIZE=500 # number of history buffer lines
options SC_NORM_ATTR="(FG_YELLOW|BG_BLACK)"
options SC_NORM_REV_ATTR="(FG_BLACK|BG_GREEN)"
options SC_KERNEL_CONS_ATTR="(FG_RED|BG_BLACK)"
options SC_KERNEL_CONS_REV_ATTR="(FG_BLACK|BG_RED)"
options CLK_USE_I8254_CALIBRATION
options CLK_USE_TSC_CALIBRATION
options NMBCLUSTERS=4096
(I post this in case something is glaringly obvious, before I start
to randomly disable half these options to see if things change)
Rest of kernel config skipped here, but can be posted if of interest
I haven't paid much attention to CPU usage of mpg123 on a 500MHz
machine with both OSen, but it's in the low single digits, and is
not as blindingly obvious as with this slow machine.
I've done a `buildworld' on this 75MHz machine for FreeBSD-current
and -stable is in progress, so I think I'll try a NetBSD build too
and see how elapsed time (many many hours) compares, not that that
is a reliable indicator of speed and efficiency either.
confused,
barry bouwsma
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