Re: [Gumstix-users] microSDHC write speed comparison

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 454-5900

What if you try copying from memory rather than dd if=/dev/zero?

It may be that when you boot from NAND it's automatically mounted in 'sync'
mode rather than 'async'.

AJ ONeal

On Mon, Sep 6, 2010 at 4:10 AM, Victor Andres <vi...@cy...> wrote:

>  From a Kingston 2GB class 4 on Overo, booted from the microSD card:
>
> root@overo:~# dd if=/dev/zero of=/zero.dat bs=1M count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1.0 GB) copied, 236.848 s, 4.4 MB/s
>
> There's about 1.1 MB/s different with the result of your experience.
>
>
> But there's something that I don't understand, if I boot from NAND and run
> the same I get only 1.2  MB/s.
>
> root@wimu:~# dd if=/dev/zero of=/media/mmcblk0p1/zero.dat bs=1M count=1000
>
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1.0 GB) copied, 859.527 s, 1.2 MB/s
>
> Regards
>
>
> ----- Original Message -----
> *From:* Cole Christensen <chr...@um...>
> *To:* General mailing list for gumstix users.<gum...@li...>
> *Sent:* Friday, September 03, 2010 7:35 PM
> *Subject:* Re: [Gumstix-users] microSDHC write speed comparison
>
> AJ,
>
> I believe your test method is flawed.
>
> My results for a (generic) Class 4 MicroSD on Overo, booted from the SD
> card:
>
> root@overo:/# dd if=/dev/zero of=/zero.dat bs=1M count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1.0 GB) copied, 190.283 s, 5.5 MB/s
>
> while your cat | dd is still reading from the disk, hence the slowdown.
>
> Yours is a test of copy speed, not pure write speed.
> I am not yet sure if my method is entirely valid either.
> Would transferring speed be artificially high when all the bits are zero?
>
> On Fri, Sep 3, 2010 at 11:13 AM, Robert Vogt IV <ro...@io...> wrote:
>
>> Hi Cole,
>>
>> Agreed.  I have some numbers for various random number generators on a
>> 16-core Itanium (RHEL 4):
>>
>> Method  Speed (MB/s)    Speed (MB/s)
>>                (saving data)   (pure generation)
>> Urandom 4.19    4.61
>> System  39.67   250.94
>> Cran32  37.64   186.29
>> Lcg     29.16   72.98
>> Rtprng  40.17   276.17
>> Isaac   42.07   375.38
>> Sfmt    43.32   563.38
>> TR1-MT  29.66   83.17
>>
>> As you can see, urandom is by far the slowest, followed by random
>> (random blocks waiting for entropy if necessary, making it quite hard
>> to get lots of data).  Of course, for write testing, one doesn't even
>> need random data...
>>
>>
>> Robert Vogt IV
>> CEO
>> IOSiX, LLC
>> 2375 Parkwood Ave
>> Ypsilanti, MI  48198
>> ro...@io...
>> P: 734-730-9690
>> F: 734-482-2337
>>
>>
>>
>> On Fri, Sep 3, 2010 at 4:49 AM, Cole Christensen <chr...@um...>
>> wrote:
>> >
>> >> root@overo:~# dd if=/dev/urandom of=/media/mmcblk0p1/rand.dd bs=1M
>> >> count=100
>> >
>> > If your input is urandom the bottleneck could be the random number
>> generator
>> > and not the disk.
>> >
>> >>
>> >>
>> >>
>> >> ----- Original Message -----
>> >> From: AJ ONeal
>> >> To: General mailing list for gumstix users.
>> >> Sent: Friday, September 03, 2010 2:25 AM
>> >> Subject: [Gumstix-users] microSDHC write speed comparison
>> >> I'm testing out various brands and classes of microSDHC to see which
>> >> actually perform as they should and whether the microSDHC or the
>> gumstix
>> >> data bus is my write speed bottleneck.
>> >> http://fastr.github.com/articles/testing-file-write-speeds.html
>> >> So far I would recommend Kingston. It's more expensive, but it performs
>> >> well. I should have a class 10 of theirs soon to test against.
>> >> AJ ONeal
>> >>
>> >> ________________________________
>> >>
>> >>
>> >>
>> ------------------------------------------------------------------------------
>> >> This SF.net Dev2Dev email is sponsored by:
>> >>
>> >> Show off your parallel programming skills.
>> >> Enter the Intel(R) Threading Challenge 2010.
>> >> http://p.sf.net/sfu/intel-thread-sfd
>> >>
>> >> ________________________________
>> >>
>> >> _______________________________________________
>> >> gumstix-users mailing list
>> >> gum...@li...
>> >> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>> >>
>> >>
>> >>
>> ------------------------------------------------------------------------------
>> >> This SF.net Dev2Dev email is sponsored by:
>> >>
>> >> Show off your parallel programming skills.
>> >> Enter the Intel(R) Threading Challenge 2010.
>> >> http://p.sf.net/sfu/intel-thread-sfd
>> >> _______________________________________________
>> >> gumstix-users mailing list
>> >> gum...@li...
>> >> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>> >>
>> >
>> >
>> >
>> ------------------------------------------------------------------------------
>> > This SF.net Dev2Dev email is sponsored by:
>> >
>> > Show off your parallel programming skills.
>> > Enter the Intel(R) Threading Challenge 2010.
>> > http://p.sf.net/sfu/intel-thread-sfd
>> > _______________________________________________
>> > gumstix-users mailing list
>> > gum...@li...
>> > https://lists.sourceforge.net/lists/listinfo/gumstix-users
>> >
>> >
>>
>>
>> ------------------------------------------------------------------------------
>> This SF.net Dev2Dev email is sponsored by:
>>
>> Show off your parallel programming skills.
>> Enter the Intel(R) Threading Challenge 2010.
>> http://p.sf.net/sfu/intel-thread-sfd
>> _______________________________________________
>> gumstix-users mailing list
>> gum...@li...
>> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>>
>
>  ------------------------------
>
>
> ------------------------------------------------------------------------------
> This SF.net Dev2Dev email is sponsored by:
>
> Show off your parallel programming skills.
> Enter the Intel(R) Threading Challenge 2010.
> http://p.sf.net/sfu/intel-thread-sfd
>
> ------------------------------
>
> _______________________________________________
> gumstix-users mailing list
> gum...@li...
> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>
>
>
> ------------------------------------------------------------------------------
> This SF.net Dev2Dev email is sponsored by:
>
> Show off your parallel programming skills.
> Enter the Intel(R) Threading Challenge 2010.
> http://p.sf.net/sfu/intel-thread-sfd
> _______________________________________________
> gumstix-users mailing list
> gum...@li...
> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>
>