Linux users want better desktop performance (Screw data. Prioritize code)

[Bill Davidsen]

Kevin Martin wrote:
> <snip>
>> I read that [3] article and the first two things I noticed were the
>> reference to "small RAM" which in the days of $11/GB RAM is rare, and
>> that the author didn't touch the "dirty" tuning parameters, which are
>> better suited to controlling the behavior of i/o buffers. He didn't
>> mention tuning read ahead to speed reading of  application off the
>> disk (which limits response even if lots of memory is free). In short
>> the article is based on one trick, not a balanced approach to getting
>> both responsive performance and good i/o performance.
>>
>> I regularly handle images 4x the size of memory, and in 33 days uptime
>> have written a total of 109MB (from iostat) to swap. A balanced tune
>> is far nicer than cranking swappiness as low as it will go and keeping
>> crap in memory which is not needed (left over initialization code,
>> error messages you never see, etc).
>>
>>> [1]
>>> http://rudd-o.com/en/linux-and-free-software/tales-from-responsivenessland-why-linux-feels-slow-and-how-to-fix-that
>>>
>>> [2]
>>> http://apcmag.com/interview_with_con_kolivas_part_1_computing_is_boring.htm
>>>
>>> [3] http://apcmag.com/why_i_quit_kernel_developer_con_kolivas.htm
>>>
>>
> 
> Bill, 
> 
> You don't mention what types of tuning you've done to enforce a
> "balanced approach".  Any suggestions are greatly appreciated!
> 
Actually I did, there are some "dirty" parameters right where the swappiness 
lives, in /proc/sys/vm and making dirty_expire smaller pushes large writes out 
faster. You can also adjust the dirty*ratio values to speed cleansing. The 
details are in the "Documentation" directory of the kernel source (and elsewhere 
I guess, never looked).

using the "blockdev --setra" option to use a larger readahead will speed reads 
from the disk and bring programs in faster. Note that it also uses more memory, 
play with care on a small memory machine. This can take 30% off of boot time on 
some laptops with slow disk and GB+ ram (most recent laptops, in other words). 
Try powers of two starting at 4096 or so until it stops feeling better.


-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot