Re: [9front] Some SMP performance measurements.

[Steve Simon <steve@quintile.net>]

hi,

out of interest what are you building, the kernel?

also, remember the caches in the file servers so try repeating the build several times on a quiet machine.

personally i find plan9’s linker is the bottleneck when doing builds, and i have always found builds to be cpu bound.

-Steve

> On 12 Mar 2020, at 2:40 am, Trevor Higgins <plan9fullfrontal@qs.co.nz> wrote:
> 
> Using 'mk'  just because it is there and manages the multitasking for me. I used timing of a build to measure performance.
> Comparing a standard build from ramfs with both source objects files in the same file service , and a build where the source and object files were split between 8 ramfs mount points.
> 
> I have found that the Fileservices are a significant source of throttling of performance. Performance using hjfs shows ramfs is not causing unexpected delay and ramfs always shows significant increase in performance over hjfs.
> 
> Splitting the build directories showed a 4 fold decrease in real build time with fewer processors/threads.
> For a build with a single FS serving the source and a single FS serving the object storage, there is no real saving in time after 4 threads. The build process is completely IO bound with 6 threads.
> 
> The split build is IO bound with 8 threads but with better utilization resulting in substantially lower build times.
> 
> No criticism of Plan9 or anything or anyone, just looking at the numbers to help figure out how to design some software I am writing. SMP may not be much use to me in my application.
> 
> 
> -- 
> 
> We need another plan