Improve Pi desktop performance

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TLDR: If your Pi 3B/3B+ desktop is slow, particularly when web browsing,  

then buy a Samsung MUF-64BE3 USB 3.1 Flash Drive BAR PLUS

I decided to get a 3B+ and shift all my Pi's around. The 3B+ took over  
the role of my main workhorse -Perforce source control server, weather  
station web server, ssh gateway, plus some development work and web  
browsing, attached to a Sandisk 64GB SSD with a USB to SATA interface.  
The main reason behind it being the faster Ethernet would help with a  
lot of those roles.

The 3B was then moved to replace the aging 2B used for web browsing on  
the bedroom TV, particularly as it's Samsung MUF-BA 32GB stick was  
starting to become unreliable (lasted about 3 years compared to a year  
for an SD card). However, as soon as I fired up the chromium browser on  
Raspbian/Mate it really crawled, the CPU monitor on the task bar showing  

almost entirely I/O wait for periods of up to 30 seconds. The 2B never  
did this, nor the 3B in its old role.

I first thought it could be the 3B's internal WiFi (the 2B was using an  
official Pi WiFi dongle), but it was the same even when I dug out a long  

Ethernet cable. I then realised due to the Pi only having 1GB of memory  
it was swapping when the browser was active, and the SD card was the  
bottle neck.

Although the new Samsung EVO Plus 32GB SD card I had out in has a good  
top speed when used with a USB3 card reader on a PC, the key figure of  
the 4K random write speed was pathetic:-

-----------------------------------------------------------------------
CrystalDiskMark 3.0.3 x64 (C) 2007-2013 hiyohiyo
                            Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

            Sequential Read :    78.304 MB/s
           Sequential Write :    27.758 MB/s
          Random Read 512KB :    61.014 MB/s
         Random Write 512KB :    19.979 MB/s
     Random Read 4KB (QD=1) :     2.688 MB/s [   656.2 IOPS]
    Random Write 4KB (QD=1) :     0.102 MB/s [    25.0 IOPS]
    Random Read 4KB (QD32%) :     2.699 MB/s [   658.9 IOPS]
   Random Write 4KB (QD32%) :     0.103 MB/s [    25.2 IOPS]

   Test : 50 MB [D: 0.0% (0.0/63.9 MB)] (x1)
   Date : 2018/09/01 0:25:34
     OS : Windows 8.1  [6.3 Build 9600] (x64)

The Samsung and SandDisk C4 and C6 cards I've used in my other Pis give  
4K random reads and writes of around 4MB/s and 1.5MB/s - twice as fast  
reading and crucially 15x as fast writing. The old Samsung MUF-BA 32GB  
stick had 4K speeds of 4.8MB/s and 0.6MB/s when I retested it, I'm sure  
it was a lot quicker when new, but still considerably faster than that  
SD card.

I was going to buy another stick, but noticed that it has been replaced  

, I  
bought the Samsung MUF-64BE3 https://www.amazon.co.uk/gp/product/B07CVWWW
TL/

This has vastly improved figures:-
-----------------------------------------------------------------------
CrystalDiskMark 3.0.3 x64 (C) 2007-2013 hiyohiyo
                            Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

            Sequential Read :   222.132 MB/s
           Sequential Write :    26.446 MB/s
          Random Read 512KB :   165.914 MB/s
         Random Write 512KB :    22.447 MB/s
     Random Read 4KB (QD=1) :    11.431 MB/s [  2790.7 IOPS]
    Random Write 4KB (QD=1) :     8.623 MB/s [  2105.3 IOPS]
    Random Read 4KB (QD32%) :    12.477 MB/s [  3046.2 IOPS]
   Random Write 4KB (QD32%) :     9.407 MB/s [  2296.6 IOPS]

   Test : 1000 MB [D: 0.0% (0.0/59.8 GB)] (x1)
   Date : 2018/08/31 18:52:05
     OS : Windows 8.1  [6.3 Build 9600] (x64)

The 4K write performance is astonishing, and not far off a small SSD  
drive. When used with the Pi 3B its now transformed, web browsing is  
pretty quick (not much difference to my i3 laptop on battery power), and  

not a single hint of I/O wait on the task monitor. As I'm only using  
about 16G of the 64GB, it should last a number of years before using up  
it's write life. So definitely a worthwhile addition.

BTW the Pi 2B has moved to the kitchen TV to replace a 1B running  
OpenElec, which has given it a huge boost in performance for viewing  
pictures and videos, and it no longer struggles with Youtube and iPlayer  

plug-ins. The 1B will join other older Pi's and Pi zeros acting as  
sensors around the house.

---druck


Re: Improve Pi desktop performance
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Thanks, good to know.  My favoured USB stick until recently has been the
Sandisk Extreme USB 3.0, which contains a SATA SSD inside and a SATA-USB
bridge.  But this is now discontinued, and the replacement 128GB Extreme Pro
is a bit pricey when you only need 32GB.

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For the record, IOPS on SSDs are of the region of 50-100K at QD32%, a bit
less at QD=1.  So it's not quite there, but about comparable with the
Sandisk Extreme.  Seems the USB in the way doesn't help the latency.  Still,
better than SD cards where some get IOPS of below 10.

Theo

Re: Improve Pi desktop performance
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[snipped]

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So you are booting from and running the OS from USB flash drive instead of a normal SD card? Is that true that in general, USB flash drives have better 4K performance than the normal SD cards?  



Re: Improve Pi desktop performance
On 05/09/2018 01:57, abc wrote:
Quoted text here. Click to load it


Yes, its very simple to do. google for "Raspberry Pi boot from USB"

Quoted text here. Click to load it

Not in general. I had a 32GB HP flash drive which had great large file  
performance, but only did 0.003 MB/s for 4K read and write - far worse  
than my most crap SD card.

That's why I feel its worth passing on the details of a good USB stick  
like the Samsung.

---druck


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