Hi All,
I have an LSI HBA card (LSI SAS 9207-8i) with 12 7200rpm SAS drives
attached. When it's formated with mdraid6+ext4 I get about 1200MB/s
for multiple streaming random reads with iozone. With btrfs in
3.9.0-rc4 I can also get about 1200MB/s, but only with one stream at a
time.
As soon as I add a second (or more), the speed will drop to about
750MB/s. If I add more streams (10, 20, etc), the total throughput
stays at around 750MB/s. I only see the full 1200MB/s in btrfs when
I'm running a single read at a time (e.g. sequential reads with dd,
random reads with iozone, etc).
This feel like a bug or mis-configuration on my system. As if can
read at the full speed, but just only with one stream running at a
time. The options I have tried varying are "-l 64k" with mkfs.btrfs,
and "-o thread_pool=16" when mounting. But, neither of those options
seem to change the behaviour.
Anyone know any reasons why I would see the speed drop when going from
one to more then one stream at a time with btrfs raid6? We would like
to use btrfs (mostly for snapshots), but we do need to get the full
1200MB/s streaming speeds too..
Thanks,
Matt
___
Here's some example output..
Single thread = ~1.1GB/s
_____
kura1 persist # sysctl vm.drop_caches=1 ; dd if=/dev/zero
of=/var/data/persist/testfile bs=640k count=20000
vm.drop_caches = 1
20000+0 records in
20000+0 records out
13107200000 bytes (13 GB) copied, 7.14139 s, 1.8 GB/s
kura1 persist # sysctl vm.drop_caches=1 ; dd of=/dev/null
if=/var/data/persist/testfile bs=640k
vm.drop_caches = 1
20000+0 records in
20000+0 records out
13107200000 bytes (13 GB) copied, 11.2666 s, 1.2 GB/s
kura1 persist # sysctl vm.drop_caches=1 ; dd of=/dev/null
if=/var/data/persist/testfile bs=640k
vm.drop_caches = 1
20000+0 records in
20000+0 records out
13107200000 bytes (13 GB) copied, 11.5005 s, 1.1 GB/s
____
1 thread = ~1000MB/s ...
___
kura1 scripts # sysctl vm.drop_caches=1 ; for j in {1..1} ; do dd
of=/dev/null if=/var/data/persist/testfile_$j bs=640k ; done
vm.drop_caches = 1
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 6.52018 s, 1.0 GB/s
kura1 scripts # sysctl vm.drop_caches=1 ; for j in {1..1} ; do dd
of=/dev/null if=/var/data/persist/testfile_$j bs=640k ; done
vm.drop_caches = 1
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 6.55731 s, 999 MB/s
___
2 threads = ~750MB/s combined...
___
# sysctl vm.drop_caches=1 ; for j in {1..2} ; do dd of=/dev/null
if=/var/data/persist/testfile_$j bs=640k & done
vm.drop_caches = 1
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 17.5068 s, 374 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 17.7599 s, 369 MB/s
___
20 threads = ~750MB/s combined...
___
# sysctl vm.drop_caches=1 ; for j in {1..20} ; do dd of=/dev/null
if=/var/data/persist/testfile_$j bs=640k & done
vm.drop_caches = 1
kura1 scripts # 10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 168.223 s, 39.0 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 168.275 s, 38.9 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 169.466 s, 38.7 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 169.606 s, 38.6 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.503 s, 38.4 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.629 s, 38.4 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.633 s, 38.4 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.744 s, 38.4 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.844 s, 38.4 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 170.896 s, 38.3 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.027 s, 38.3 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.135 s, 38.3 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.389 s, 38.2 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.414 s, 38.2 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.674 s, 38.2 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.897 s, 38.1 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.956 s, 38.1 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 171.995 s, 38.1 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 172.044 s, 38.1 MB/s
10000+0 records in
10000+0 records out
6553600000 bytes (6.6 GB) copied, 172.08 s, 38.1 MB/s
____
### Similar results with random reads in iozone...
1 thread = ~1000MB/s
_____
kura1 scripts # for j in {1..1} ; do sysctl vm.drop_caches=1 ; iozone
-f /var/data/10GBfolders/folder$j/iozone.DUMMY.1 -c -M -r 5120k -s 2g
-i 1 -w -+A 1 | tail -n 5 & done
vm.drop_caches = 1
[1] 22298
kura1 scripts #
random random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 1077376 7288014
iozone test complete.
____
2 threads = ~750 MB/s combined...
___
# for j in {1..2} ; do sysctl vm.drop_caches=1 ; iozone -f
/var/data/10GBfolders/folder$j/iozone.DUMMY.1 -c -M -r 5120k -s 2g -i
1 -w -+A 1 | tail -n 5 & done
vm.drop_caches = 1
[1] 22302
vm.drop_caches = 1
[2] 22305
kura1 scripts #
random random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 368864 5090095
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 366834 5105457
iozone test complete.
20 threads = ~750MB/s combined...
___
# for j in {1..20} ; do sysctl vm.drop_caches=1 ; iozone -f
/var/data/10GBfolders/folder$j/iozone.DUMMY.1 -c -M -r 5120k -s 2g -i
1 -w -+A 1 | tail -n 5 & done
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 40424 6459500
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 39678 5749776
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 39548 5417189
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38988 5924904
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38484 1963969
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38556 1793398
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38610 1343518
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38346 1394609
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38367 1163930
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38375 1143491
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38647 1046416
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38180 1115287
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38086 1192537
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38356 1120244
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38293 1138119
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 37966 1273741
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 38059 1201688
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 37947 1243573
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 37965 1245834
iozone test complete.
random
random bkwd record stride
KB reclen write rewrite read reread read
write read rewrite read fwrite frewrite fread freread
2097152 5120 37840 1354806
iozone test complete.
___
### Typical dstat output during multi-thread read running and then
finish and go idle...
___
----total-cpu-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| read writ| recv send| in out | int csw
0 10 28 62 0 0| 716M 0 | 582B 870B| 0 0 |4398 16k
0 12 28 59 0 0| 728M 0 | 454B 982B| 0 0 |4665 16k
0 12 25 63 0 0| 761M 0 | 454B 1112B| 0 0 |4661 16k
0 11 22 66 0 0| 719M 0 | 390B 742B| 0 0 |4519 16k
0 13 21 65 0 0| 741M 0 | 524B 1036B| 0 0 |4706 16k
0 17 19 63 0 0| 706M 0 |3302B 3558B| 0 0 |4638 15k
0 16 17 67 0 0| 721M 0 | 16k 15k| 0 0 |5002 17k
2 72 7 19 0 0| 514M 0 | 454B 486B| 0 0 |4174 8591
3 97 0 0 0 0| 0 0 | 788B 2884B| 0 0 |1280 380
1 38 61 0 0 0| 0 0 |1428B 7460B| 0 0 | 888 346
0 0 100 0 0 0| 0 0 | 582B 678B| 0 0 | 92 106
0 0 100 0 0 0| 0 0 |1606B 1766B| 0 0 | 66 59
0 0 100 0 0 0| 0 4096B| 390B 742B| 0 0 | 90 112
0 0 100 0 0 0| 0 0 | 454B 486B| 0 0 | 45 65
0 0 100 0 0 0| 0 0 | 454B 614B| 0 0 | 56 77
___
### Some system info...
____
## Kernel = 3.9.0-rc4
# uname -a
Linux server 3.9.0-rc4 #4 SMP Fri Apr 5 00:58:28 UTC 2013 x86_64
Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz GenuineIntel GNU/Linux
# grep MemTotal /proc/meminfo
MemTotal: 65975896 kB
___
## 12 2.3 GHz Xeon cores...
kura1 scripts # head -n 26 /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 45
model name : Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
stepping : 6
microcode : 0x616
cpu MHz : 2301.000
cache size : 15360 KB
physical id : 0
siblings : 12
core id : 0
cpu cores : 6
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx
pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl
xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor
ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2
x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb
xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips : 4600.26
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
___
## Asus Z9PA-U8 MB
# dmidecode --type 1
# dmidecode 2.11
SMBIOS 2.7 present.
Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: ASUSTeK COMPUTER INC.
Product Name: Z9PA-U8 Series
Version: 1.0X
Serial Number: To be filled by O.E.M.
UUID: 598C1800-5BCB-11D9-8F58-3085A9A7CBC7
Wake-up Type: Power Switch
SKU Number: SKU
Family: To be filled by O.E.M.
____
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