Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation

[Lukas Czerner <lczerner@redhat.com>]

On Fri, 26 Nov 2010, Mark Lord wrote:

> On 10-11-25 11:24 AM, Greg Freemyer wrote:
> > 
> > I'm away from my systems today, but is there an easy way to tweak
> > wiper.sh or hdparm to cause only a single range per trim command.
> > 
> > I'm curious if for the Sandforce that would still be in the 90 second
> > range, or closer to 64x that.
> 
> Good question.  The Indilinx based drives would be in the 64x range,
> no doubt there.  But I don't know about the Sandforce.
> 
> And I don't think I'm willing to inflict so many life-shortening erase
> cycles onto it just to find out.
> 
> One thing to note:  the execution time for TRIM does vary depending upon
> whether the (logical) LBAs are already mostly in a "trimmed" state or not.
> 
> So anyone aspiring to benchmark this stuff will need to keep that in mind.
> My timings above were for "already trimmed" cases.  I would expect them
> to be much slower (2x - 3x) if the sectors all held data prior to trim.
> 
> Cheers
> 

I have already did some TRIM benchmarking, but especially regarding trim
extent size. Also there is a tool test-discard for that purpose, so it
may be handy for anyone trying to do something similar.

http://people.redhat.com/lczerner/discard/

Thanks!

-Lukas