On Thu, Aug 02, 2012 at 11:21:51PM +0200, Martin Steigerwald wrote:

quoted

Yep, my du -sh tests do show that ext4 is 2x faster than btrfs.
Obviously it's sending IO in a way that either the IO subsystem, linux
driver, or drive prefer.

But only on reads.

Yes. I was focussing on the simple case. SSDs can be slower than hard
drives on writes, and now you're getting into deep firmware magic for
corner cases, so I didn't want to touch that here :)
 

WTF?

Hey, did you adapt the size= keyword? It seems fio 2.0.8 can do completely
without it.

I left it as is:
[global]
ioengine=libaio
direct=1
filename=/dev/sda
size=476940m
bsrange=2k-16k

[zufälliglesen]
rw=randread
runtime=60

[sequentielllesen]
stonewall
rw=read
runtime=60

I just removed it now.

Okay, one further idea: Remove the bsrange to just test with 4k blocks.

Ok, there you go:
[global]
ioengine=libaio
direct=1
filename=/dev/sda
blocksize=4k
blockalign=4k

[zufälliglesen]
rw=randread
runtime=60

[sequentielllesen]
stonewall
rw=read
runtime=60

gandalfthegreat:~# fio --readonly ./fio.job4
zufälliglesen: (g=0): rw=randread, bs=4K-4K/4K-4K, ioengine=libaio, iodepth=1
sequentielllesen: (g=1): rw=read, bs=4K-4K/4K-4K, ioengine=libaio, iodepth=1
2.0.8
Starting 2 processes
Jobs: 1 (f=1): [_R] [66.9% done] [1476K/0K /s] [369 /0  iops] [eta 01m:00s]
zufälliglesen: (groupid=0, jobs=1): err= 0: pid=3614
  read : io=60832KB, bw=1013.7KB/s, iops=253 , runt= 60012msec
    slat (usec): min=4 , max=892 , avg=24.36, stdev=16.05
    clat (usec): min=2 , max=27575 , avg=3915.39, stdev=4990.69
     lat (usec): min=44 , max=27591 , avg=3940.35, stdev=4991.99
    clat percentiles (usec):
     |  1.00th=[   41],  5.00th=[   46], 10.00th=[   51], 20.00th=[   66],
     | 30.00th=[  113], 40.00th=[  163], 50.00th=[  205], 60.00th=[ 4960],
     | 70.00th=[ 5856], 80.00th=[11584], 90.00th=[12480], 95.00th=[12608],
     | 99.00th=[14272], 99.50th=[17280], 99.90th=[18816], 99.95th=[21120],
     | 99.99th=[22912]
    bw (KB/s)  : min=  253, max= 2520, per=100.00%, avg=1014.86, stdev=364.74
    lat (usec) : 4=0.05%, 10=0.01%, 20=0.01%, 50=8.07%, 100=1iiiiiiii9.94%
    lat (usec) : 250=26.26%, 500=2.78%, 750=0.30%, 1000=0.09%
    lat (msec) : 2=0.12%, 4=0.07%, 10=20.75%, 20=21.51%, 50=0.05%
  cpu          : usr=0.31%, sys=0.88%, ctx=15250, majf=0, minf=23
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=15208/w=0/d=0, short=r=0/w=0/d=0
sequentielllesen: (groupid=1, jobs=1): err= 0: pid=3636
  read : io=88468KB, bw=1474.3KB/s, iops=368 , runt= 60009msec
    slat (usec): min=3 , max=340 , avg=16.46, stdev=10.23
    clat (usec): min=1 , max=27356 , avg=2692.99, stdev=4564.76
     lat (usec): min=30 , max=27370 , avg=2709.87, stdev=4566.31
    clat percentiles (usec):
     |  1.00th=[   27],  5.00th=[   29], 10.00th=[   31], 20.00th=[   35],
     | 30.00th=[   47], 40.00th=[   61], 50.00th=[   78], 60.00th=[  107],
     | 70.00th=[  270], 80.00th=[ 5856], 90.00th=[11712], 95.00th=[12608],
     | 99.00th=[16512], 99.50th=[17536], 99.90th=[18816], 99.95th=[19584],
     | 99.99th=[21120]
    bw (KB/s)  : min=  282, max= 5096, per=100.00%, avg=1474.40, stdev=899.36
    lat (usec) : 2=0.05%, 4=0.01%, 20=0.02%, 50=32.45%, 100=24.61%
    lat (usec) : 250=12.52%, 500=1.40%, 750=0.03%, 1000=0.03%
    lat (msec) : 2=0.02%, 4=0.03%, 10=13.95%, 20=14.85%, 50=0.03%
  cpu          : usr=0.33%, sys=0.90%, ctx=22176, majf=0, minf=25
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=22117/w=0/d=0, short=r=0/w=0/d=0

Run status group 0 (all jobs):
   READ: io=60832KB, aggrb=1013KB/s, minb=1013KB/s, maxb=1013KB/s, mint=60012msec, maxt=60012msec

Run status group 1 (all jobs):
   READ: io=88468KB, aggrb=1474KB/s, minb=1474KB/s, maxb=1474KB/s, mint=60009msec, maxt=60009msec

Disk stats (read/write):
  sda: ios=54013/1836, merge=291/17, ticks=251660/11052, in_queue=262668, util=99.51%


and the same test with blockalign=512k:
gandalfthegreat:~# fio --readonly ./fio.job4 # blockalign=512k
fio: Any use of blockalign= turns off randommap
zufälliglesen: (g=0): rw=randread, bs=4K-4K/4K-4K, ioengine=libaio, iodepth=1
sequentielllesen: (g=1): rw=read, bs=4K-4K/4K-4K, ioengine=libaio, iodepth=1
2.0.8
Starting 2 processes
Jobs: 1 (f=1): [_R] [66.9% done] [4180K/0K /s] [1045 /0  iops] [eta 01m:00s]
zufälliglesen: (groupid=0, jobs=1): err= 0: pid=3679
  read : io=56096KB, bw=957355 B/s, iops=233 , runt= 60001msec
    slat (usec): min=4 , max=344 , avg=27.73, stdev=15.51
    clat (usec): min=2 , max=38954 , avg=4244.27, stdev=5153.32
     lat (usec): min=44 , max=38980 , avg=4272.70, stdev=5154.68
    clat percentiles (usec):
     |  1.00th=[   42],  5.00th=[   46], 10.00th=[   53], 20.00th=[   69],
     | 30.00th=[  120], 40.00th=[  169], 50.00th=[  211], 60.00th=[ 5024],
     | 70.00th=[ 5920], 80.00th=[11584], 90.00th=[12480], 95.00th=[12608],
     | 99.00th=[16768], 99.50th=[17536], 99.90th=[18560], 99.95th=[20096],
     | 99.99th=[37632]
    bw (KB/s)  : min=  263, max= 3133, per=100.00%, avg=935.09, stdev=392.66
    lat (usec) : 4=0.05%, 10=0.03%, 20=0.01%, 50=7.84%, 100=19.12%
    lat (usec) : 250=25.84%, 500=1.61%, 750=0.08%, 1000=0.05%
    lat (msec) : 2=0.06%, 4=0.08%, 10=21.99%, 20=23.17%, 50=0.06%
  cpu          : usr=0.29%, sys=0.94%, ctx=14069, majf=0, minf=25
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=14024/w=0/d=0, short=r=0/w=0/d=0
sequentielllesen: (groupid=1, jobs=1): err= 0: pid=3703
  read : io=99592KB, bw=1659.7KB/s, iops=414 , runt= 60008msec
    slat (usec): min=4 , max=186 , avg=15.83, stdev= 9.95
    clat (usec): min=1 , max=25530 , avg=2390.79, stdev=4340.79
     lat (usec): min=28 , max=25539 , avg=2407.01, stdev=4342.90
    clat percentiles (usec):
     |  1.00th=[   26],  5.00th=[   28], 10.00th=[   30], 20.00th=[   34],
     | 30.00th=[   43], 40.00th=[   57], 50.00th=[   72], 60.00th=[   91],
     | 70.00th=[  155], 80.00th=[ 5152], 90.00th=[11712], 95.00th=[12480],
     | 99.00th=[12992], 99.50th=[16768], 99.90th=[18560], 99.95th=[18816],
     | 99.99th=[21632]
    bw (KB/s)  : min=  269, max= 8465, per=100.00%, avg=1663.84, stdev=1367.82
    lat (usec) : 2=0.01%, 4=0.02%, 20=0.01%, 50=35.42%, 100=26.00%
    lat (usec) : 250=11.29%, 500=1.31%, 750=0.05%, 1000=0.01%
    lat (msec) : 2=0.04%, 4=0.02%, 10=12.55%, 20=13.25%, 50=0.01%
  cpu          : usr=0.31%, sys=0.99%, ctx=24963, majf=0, minf=25
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=24898/w=0/d=0, short=r=0/w=0/d=0

Run status group 0 (all jobs):
   READ: io=56096KB, aggrb=934KB/s, minb=934KB/s, maxb=934KB/s, mint=60001msec, maxt=60001msec

Run status group 1 (all jobs):
   READ: io=99592KB, aggrb=1659KB/s, minb=1659KB/s, maxb=1659KB/s, mint=60008msec, maxt=60008msec

Disk stats (read/write):
  sda: ios=55021/1637, merge=72/39, ticks=240896/12080, in_queue=252912, util=99.59%

quoted

Since I've gotten 2 SSDs to make sure I didn't get one bad one, and that the
company is greating great reviews for them, I'm now pretty sure that
it's either a problem with a linux driver, which is interesting for us
all to debug :)

Either that or there possible is some firmware update? But then those
reviews would mention it I bet.

 
So far, there are no firmware updates from mine, I checked right after
unboxing it :)

quoted

I'll try plugging this SSD in a totally different PC and see what happens.
This may say if it's an AHCI/intel sata driver problem.

Seems we will continue until someone starts to complain here. Maybe
another list will be more approbiate? But then this thread has it all
in one ;). Adding a CC with some introductory note might be approbiate.
Its your problem, so you decide ;). I´d suggest the fio mailing list,
there are other performance people how may want to chime in.

 
Actually you know the lists and people involved more than me. I'd be
happy if you added a Cc to another list you think is best, and we can
move there.

Another idea: Is there anything funny in SMART values (smartctl -a
and possibly even -x)? Well I gather these SSDs are new, but still.

smartctl -a /dev/sda
(snipped)
SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       36
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       7
177 Wear_Leveling_Count     0x0013   099   099   000    Pre-fail  Always       -       9
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail  Always       -       0
181 Program_Fail_Cnt_Total  0x0032   100   100   010    Old_age   Always       -       0
182 Erase_Fail_Count_Total  0x0032   100   100   010    Old_age   Always       -       0
183 Runtime_Bad_Block       0x0013   100   100   010    Pre-fail  Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   058   040   000    Old_age   Always       -       42
195 Hardware_ECC_Recovered  0x001a   200   200   000    Old_age   Always       -       0
199 UDMA_CRC_Error_Count    0x003e   253   253   000    Old_age   Always       -       0
235 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       4
241 Total_LBAs_Written      0x0032   099   099   000    Old_age   Always       -       433339112


smartctl -x /dev/sda
smartctl 5.41 2011-06-09 r3365 [x86_64-linux-3.5.0-amd64-preempt-noide-20120410] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG SSD 830 Series
Serial Number:    S0WGNEAC400484
LU WWN Device Id: 5 002538 043584d30
Firmware Version: CXM03B1Q
User Capacity:    512,110,190,592 bytes [512 GB]
Sector Size:      512 bytes logical/physical
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   8
ATA Standard is:  ACS-2 revision 2
Local Time is:    Thu Aug  2 14:42:08 2012 PDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x83)	Offline data collection activity
					is in a Reserved state.
					Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0)	The previous self-test routine completed
					without error or no self-test has ever 
					been run.
Total time to complete Offline 
data collection: 		( 1980) seconds.
Offline data collection
capabilities: 			 (0x5b) SMART execute Offline immediate.
					Auto Offline data collection on/off support.
					Suspend Offline collection upon new
					command.
					Offline surface scan supported.
					Self-test supported.
					No Conveyance Self-test supported.
					Selective Self-test supported.
SMART capabilities:            (0x0003)	Saves SMART data before entering
					power-saving mode.
					Supports SMART auto save timer.
Error logging capability:        (0x01)	Error logging supported.
					General Purpose Logging supported.
Short self-test routine 
recommended polling time: 	 (   2) minutes.
Extended self-test routine
recommended polling time: 	 (  33) minutes.

SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
  5 Reallocated_Sector_Ct   PO--CK   100   100   010    -    0
  9 Power_On_Hours          -O--CK   099   099   000    -    36
 12 Power_Cycle_Count       -O--CK   099   099   000    -    7
177 Wear_Leveling_Count     PO--C-   099   099   000    -    9
179 Used_Rsvd_Blk_Cnt_Tot   PO--C-   100   100   010    -    0
181 Program_Fail_Cnt_Total  -O--CK   100   100   010    -    0
182 Erase_Fail_Count_Total  -O--CK   100   100   010    -    0
183 Runtime_Bad_Block       PO--C-   100   100   010    -    0
187 Reported_Uncorrect      -O--CK   100   100   000    -    0
190 Airflow_Temperature_Cel -O--CK   058   040   000    -    42
195 Hardware_ECC_Recovered  -O-RC-   200   200   000    -    0
199 UDMA_CRC_Error_Count    -OSRCK   253   253   000    -    0
235 Unknown_Attribute       -O--C-   099   099   000    -    4
241 Total_LBAs_Written      -O--CK   099   099   000    -    433352008
                            ||||||_ K auto-keep
                            |||||__ C event count
                            ||||___ R error rate
                            |||____ S speed/performance
                            ||_____ O updated online
                            |______ P prefailure warning

General Purpose Log Directory Version 1
SMART           Log Directory Version 1 [multi-sector log support]
GP/S  Log at address 0x00 has    1 sectors [Log Directory]
GP/S  Log at address 0x01 has    1 sectors [Summary SMART error log]
GP/S  Log at address 0x02 has    2 sectors [Comprehensive SMART error log]
GP/S  Log at address 0x03 has    2 sectors [Ext. Comprehensive SMART error log]
GP/S  Log at address 0x06 has    1 sectors [SMART self-test log]
GP/S  Log at address 0x07 has    2 sectors [Extended self-test log]
GP/S  Log at address 0x09 has    1 sectors [Selective self-test log]
GP/S  Log at address 0x10 has    1 sectors [NCQ Command Error]
GP/S  Log at address 0x11 has    1 sectors [SATA Phy Event Counters]
GP/S  Log at address 0x80 has   16 sectors [Host vendor specific log]
GP/S  Log at address 0x81 has   16 sectors [Host vendor specific log]
GP/S  Log at address 0x82 has   16 sectors [Host vendor specific log]
GP/S  Log at address 0x83 has   16 sectors [Host vendor specific log]
(snip)

SMART Extended Comprehensive Error Log Version: 1 (2 sectors)
No Errors Logged

SMART Extended Self-test Log Version: 1 (2 sectors)
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%        27         -
# 2  Short offline       Completed without error       00%         8         -

SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.

Warning: device does not support SCT Commands
SATA Phy Event Counters (GP Log 0x11)
ID      Size     Value  Description
0x0001  2            0  Command failed due to ICRC error
0x0002  2        49152  R_ERR response for data FIS
0x0003  2        53248  R_ERR response for device-to-host data FIS
0x0004  2        57344  R_ERR response for host-to-device data FIS
0x0005  2         7952  R_ERR response for non-data FIS
0x0006  2         2562  R_ERR response for device-to-host non-data FIS
0x0007  2         4096  R_ERR response for host-to-device non-data FIS
0x0008  2         7952  Device-to-host non-data FIS retries
0x0009  2         7953  Transition from drive PhyRdy to drive PhyNRdy
0x000a  2           25  Device-to-host register FISes sent due to a COMRESET
0x000b  2         6145  CRC errors within host-to-device FIS
0x000d  2         7953  Non-CRC errors within host-to-device FIS
0x000f  2         8176  R_ERR response for host-to-device data FIS, CRC
0x0010  2           15  R_ERR response for host-to-device data FIS, non-CRC
0x0012  2        49153  R_ERR response for host-to-device non-data FIS, CRC
0x0013  2        12112  R_ERR response for host-to-device non-data FIS, non-CRC

-- 
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Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
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