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Thread: SSD poor performances

  1. #1
    Join Date
    Jul 2007
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    46

    SSD poor performances

    Hello,

    I have a new PC (Asrock 970 Extreme4, FX-8120, 8GB RAM, SSD Samsung 840 128GB) with Ubuntu 12.04.
    I did the following:
    Mounting partitions with the options noatime and discard
    Minimise writes with tpmfs in RAM
    Enable Automatic TRIM => Tested OK
    Change I/O Scheduler => Tested OK
    Change swappiness

    SSD firmware is up-to-date
    M/B firmware is up-to-date

    Now I test the SSD performance according to
    https://wiki.archlinux.org/index.php/SSD_Benchmarking

    My results are:
    sudo hdparm -Tt /dev/sda
    /dev/sda:
    Timing cached reads: 9036 MB in 2.00 seconds = 4521.54 MB/sec
    Timing buffered disk reads: 1420 MB in 3.00 seconds = 473.13 MB/sec
    dd if=tempfile of=/dev/null bs=1M count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 0.208829 s, 5.1 GB/s
    In the benchmark and other SDD tests, performances are much better:
    # hdparm -Tt /dev/sda
    Timing cached reads: 22130 MB in 2.00 seconds = 11080.54 MB/sec
    Timing buffered disk reads: 1500 MB in 3.00 seconds = 499.38 MB/sec
    # dd if=tempfile of=/dev/null bs=1M count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 0.119695 s, 9.0 GB/s
    Any idea why I have these so poor performances?
    Many thanks.

  2. #2
    Join Date
    Apr 2008
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    Ubuntu Development Release

    Re: SSD poor performances

    What makes you think that you have poor performance?

    It all looks good to me.
    Cheesemill

  3. #3
    Join Date
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    Re: SSD poor performances

    With hdparm
    Timing cached reads: 9036 MB in 2.00 seconds = 4521.54 MB/sec
    compared to
    Timing cached reads: 22130 MB in 2.00 seconds = 11080.54 MB/sec

    with dd
    1073741824 bytes (1.1 GB) copied, 0.208829 s, 5.1 GB/s
    compared to
    1073741824 bytes (1.1 GB) copied, 0.119695 s, 9.0 GB/s

    This is about half speed

  4. #4
    Join Date
    Jun 2007
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    Re: SSD poor performances

    First have you done the partition alignment correctly and turned off journalling, assuming you have used ext4 (see https://wiki.archlinux.org/index.php/Solid_State_Drives)

    Next have you run the benchmark 4-5 times as recommended. Does the System Monitor report paged memory being used or not?

    Third, I assume you're refering to the benchmarks posted on the Arch wiki for the Samsung 830 (not 840)... Without knowing the specs of the system used to create that benchmark not really possible to compare the two..

    Lastly, these are measures of sequential read access, which isn't IMHO the point of getting a SSD...
    Intel C2D E7200 || Intel DG33FB mobo || 4 GB RAM || 64 bit Lucid/ Precise Desktops || WD Caviar Black 1TB, Green 2TB; Corsair Force 3 60GB
    Dell U2412M || Palit Sonic GT 240 (OC'd NVidia card) || Logitech Quickcam Connect || Acer 3300U Scanner

  5. #5
    Join Date
    Jul 2007
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    46

    Re: SSD poor performances

    1a - When installing I had to use gparted as palimpsest gave me the error for aligment. So aligment is good.

    1b - fstab
    # / was on /dev/sda1 during installation
    UUID=59d33dc7-4511-44f4-918a-1bbdb71580b4 / ext4 noatime,discard,errors=remount-ro 0 1
    # /home was on /dev/sda3 during installation
    UUID=0c91a5c5-ed6e-4853-9545-c4f0f03aa081 /home ext4 noatime,discard,defaults 0 2

    Next-a - I run hdparm and dd lot of time, results are almost the same

    Next-b - System Monitor shows 1.2 GiB (15.3%) of 7.8 GiB
    I don't know how to see paged memory.
    BTW, why I have only 7.8 GiB as lshw see 8 GiB.

    3 - Typo Samsung 830
    Connected to a SATA3. This is half the speed and looks a huge gap for me.
    Is there other benchmak programs in UBUNTU?
    Where can I compare?

  6. #6
    Join Date
    Jul 2012
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    Kubuntu 12.04 Precise Pangolin

    Re: SSD poor performances

    I think you are believing the speeds the manufacturer advertises with too much.
    I have an SSD too, it's advertised with reads of 550MB/sec, I am quite content to get around 400MB/sec.

  7. #7
    Join Date
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    Re: SSD poor performances

    Could you try
    sudo hdparm -Tt /dev/sda
    and
    dd as describe in the link
    To clear the cache you will have instead to write
    sudo sync; echo 3 | sudo tee /proc/sys/vm/drop_caches

    Let me know

  8. #8
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    Re: SSD poor performances

    My SSD is a Corsair Force GT 60GB. Corsair claims reads up to 555 MB/s.

    Code:
    # hdparm -Tt /dev/sda
    
    /dev/sda:
     Timing cached reads:   11604 MB in  2.00 seconds = 5805.31 MB/sec
     Timing buffered disk reads: 710 MB in  3.01 seconds = 236.06 MB/sec
    Code:
    root@quokka:/# dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 4.26096 s, 252 MB/s
    root@quokka:/# sync
    root@quokka:/# echo 3 > /proc/sys/vm/drop_caches
    root@quokka:/# dd if=tempfile of=/dev/null bs=1M count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 4.24495 s, 253 MB/s
    root@quokka:/# dd if=tempfile of=/dev/null bs=1M count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 0.168984 s, 6.4 GB/s

  9. #9
    Join Date
    Jul 2007
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    Re: SSD poor performances

    It looks close to mine.
    I don't knon how they can have this high speed.

    Thank you for the test anyway.

    Do you have an answer for the 7.8 GiB RAM?

  10. #10
    Join Date
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    Kubuntu 12.04 Precise Pangolin

    Re: SSD poor performances

    Quote Originally Posted by Trompette83 View Post
    It looks close to mine.
    I don't knon how they can have this high speed.

    Do you have an answer for the 7.8 GiB RAM?
    They probably run their benchmarks in highly optimised conditions on the fastest hardware available, getting results that are far distant from real world use.

    As for your RAM, probably your BIOS reserving some memory for hardware, I wouldn't worry about it.
    Same on my system with 8GB RAM:

    Code:
    $free -m
                 total       used       free     shared    buffers     cached
    Mem:          7968       2027       5941          0         35        662
    -/+ buffers/cache:       1329       6639
    Swap:         7812          0       7812

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