svn commit: r254380 - in head/sys: kern sys

[Colin Percival]

On 08/15/13 13:29, Ivan Voras wrote:
> On 15 August 2013 22:19, Colin Percival <cperciva at freebsd.org> wrote:
>>   For workloads with R parallel reads and W parallel writes, this improves
>>   the time spent from O((R+W)^2) to O(W*(R+W)); i.e., heavy parallel-read
>>   workloads become significantly more scalable.
>>
>>   No statistically significant change in buildworld time has been measured,
>>   but synthetic tests of parallel 'dd > /dev/null' and 'openssl enc >/dev/null'
>>   with the input file cached yield dramatic (up to 10x) improvement with high
>>   (up to 128 processes) levels of parallelism.
> 
> That's interesting. Have you tried running the "blogbench" benchmark
> before & after?

No, I wasn't aware that it existed.  Given that this change applies only to
parallel operations *on the same vnode* and blogbench seems to have traffic
randomly spread between many files, I doubt there would be any difference.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid