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Groups > comp.os.linux.hardware > #3256

Re: Speed ups for a disk IO bound machine

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On 13/12/16 00:08, Peter Chant wrote:
> On 12/12/2016 08:11 AM, David Brown wrote:
> 
>> My first thought is to ask what the machine is being used for.  It is
>> not normal to have apache/php/mariadb and firefox/browsing on the same
>> machine.  Usually you have either a server (and therefore no desktop
>> processes), or a desktop (and therefore no server processes of
>> particular relevance).  So what are you doing with the system?  What is
>> it that is using the I/O ?  Is the machine really too slow, and what do
>> you /feel/ is slow on it?
>>
> 
> Home desktop / server.  I have mariadb on it and the easierst way for a
> front end for some stuff I am doing seemed to be a lamp stack.

Do you mean you are running server an active webserver on the same
system you are using for browsing, development, games, email, etc.?
That is a poor setup, for efficiency, reliability, and security.  Of
course, economics can be a factor - but if you can afford to be playing
around with SSDs and multiple disks, then you should also consider if
you should have a separate machine for the server.  A small Intel NUC
with a single disk is likely to be good enough for your LAMP stack and
mediatomb server, leaving your desktop free to be a desktop.

> 
> Also have mediatomb on it and serve files to mpd on a raspberry pi.
> Mediatomb seems to churn the disk sometimes.  Not installed right now.
> 
> 
>> My second thought is that often the best way to improve I/O performance
>> is to add more ram.  Is that a possibility with your hardware?
>>
> 
> I've got 8GB and about 40% acts as a disk cache.  I could try hunting
> down 16GB on ebay but I paid full price a year or so ago for the 8GB.
> Looking at kinfocentre right now I have 19% of my memory free, 35% in
> disk cache and 44% application data.  So would adding more ram do
> anything but add to free memory?
> 

Yes, adding memory will make a /serious/ difference when you are trying
to work as a server and a desktop - /if/ you really are having
performance issues with I/O.  But to be honest, I don't think you /are/
having I/O performance issues - I suspect you just think you are.  If
you have a lot of free memory (and 19% is quite a lot, unless you have
just stopped a large process) then you are not actually doing a lot of
I/O, because disk data is cached in ram whenever there is /any/ free ram.

With more ram, writes go faster because they stay in memory for longer
and don't get flushed to disk as often.  Reads go faster because it is
much more likely that the data is already in memory.  You also have the
option of putting /tmp on tmpfs to speed up processes that use a lot of
temporary files.

But again, I would strongly suggest you try to identify what /feels/
slow, and consider how you use the machine.  What are you doing in
parallel?  What sort of serving are you actually doing, and is it
running in parallel with desktop usage?  Why do you think your I/O is slow?

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Thread

Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-07 22:41 +0000
  Re: Speed ups for a disk IO bound machine Roger Blake <rogblake@iname.invalid> - 2016-12-08 16:44 +0000
    Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-10 11:24 +0000
      Re: Speed ups for a disk IO bound machine Roger Blake <rogblake@iname.invalid> - 2016-12-11 01:34 +0000
        Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-11 22:07 +0000
  Re: Speed ups for a disk IO bound machine Piergiorgio Sartor <piergiorgio.sartor.this.should.not.be.used@nexgo.REMOVETHIS.de> - 2016-12-10 12:43 +0100
    Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-10 20:44 +0000
      Re: Speed ups for a disk IO bound machine Piergiorgio Sartor <piergiorgio.sartor.this.should.not.be.used@nexgo.REMOVETHIS.de> - 2016-12-10 23:05 +0100
        Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-11 11:54 +0000
          Re: Speed ups for a disk IO bound machine Piergiorgio Sartor <piergiorgio.sartor.this.should.not.be.used@nexgo.REMOVETHIS.de> - 2016-12-11 14:10 +0100
            Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-11 22:46 +0000
              Re: Speed ups for a disk IO bound machine Piergiorgio Sartor <piergiorgio.sartor.this.should.not.be.used@nexgo.REMOVETHIS.de> - 2016-12-12 19:22 +0100
            Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-13 10:17 +0100
              Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-14 20:03 +0000
                Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-15 12:55 +0100
                Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-15 23:18 +0000
                Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-16 09:34 +0100
        Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-13 09:57 +0100
  Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-12 09:11 +0100
    Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-12 23:08 +0000
      Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-13 09:29 +0100
        Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-14 23:16 +0000
          Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-15 13:15 +0100
            Re: Speed ups for a disk IO bound machine Peter Chant <pete@petezilla.co.uk> - 2016-12-15 22:50 +0000
              Re: Speed ups for a disk IO bound machine David Brown <david.brown@hesbynett.no> - 2016-12-16 09:39 +0100

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