Re: high sys time, very very slow builds on new 24-core system

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Thu, Mar 24, 2011 at 04:05:07PM +0000, Eduardo Horvath wrote:
> On Thu, 24 Mar 2011, Andrew Doran wrote:
> 
> > I have a suspicion that SSD could cause issues for us because the buffer
> > cache and other parts of the I/O system are not designed with near
> > instantaneous request->response in mind, but that likely isn't at play
> > here.. Do you have logging turned on for the SSD?
> 
> Do you have a pretty standard SSD or something that's write optimized?  
> While it's probably not the cause of your performace problem since you're 
> spinning in the kernel rather than idle waiting for an interrupt, SSDs are 
> usually optimized for reads.  While they have zero seek times, the write 
> cycles tend to be slow compared to spinning media.

As I said: only the sources are on SSD.  And they have been preloaded into
the page cache by tar cf - /usr/src > /dev/null before the build.

The obj, destination, and release directories are on tmpfs.
So I am hopeful this has nothing to do with the disk subsystem!

-- 
Thor Lancelot Simon                                              
tls%panix.com@localhost
    And now he couldn't remember when this passion had flown, leaving him so
  foolish and bewildered and astray: can any man?
                                                   William Styron