[issue1556] many processes stuck in "hmrrcm", system unusable

Mon Oct 5 02:34:26 PDT 2009

Justin C. Sherrill (via DragonFly issue tracker) wrote:
Justin C. Sherrill <justin at shiningsilence.com> added the comment:

On Sun, October 4, 2009 1:29 pm, Matthew Dillon wrote:

    I would much rather work on the clustering, but if people are going
    to constantly complain about HAMMER's performance I will have to take
    2-3 months and deal with this issue first I guess.
Before we have Matt, who can work full-time on clustering - the _purpose
of this project_ - digress for months on filesystem performance, can we
quantify the actual problem?
What purpose?  Clustering is set as a goal, not a purpose.  The purpose 
is to have a good operating system that will eventually be capable of 
cluster operation.  If people don't agree that having a usable operating 
system, then I think I'm betting on the wrong horse.

Corecode's report is the only one we have, and we don't have a realistic
test scenario that measures when it happens or how much it happens.  I've
been running pkgsrc bulk builds on Hammer disks for quite a while now, and
I have not seen any noticeable change in overall run time from using UFS
to using Hammer.  Chasing a heisenbug can be very difficult.
ARE YOU KIDDING ME?  Don't you read what other people, especially Hasso 
report?

I AM NOT TALKING ABOUT THROUGHPUT!  This is all about latency.  Opening 
xterm and waiting 5 or 10 seconds for the prompt is not acceptable.

So to anybody who "can not reproduce" this issue:  stop being such 
obnoxious smartasses.  There ARE serious problems, and anybody who is 
just trying to reproduce this will notice issues at once.

I think it's as simple as that:  If you don't see problems, you're not 
qualified to talk.

The best featureful file system is worth nothing if nobody can use it 
because it just performs badly.  Now is the time to address this before 
we complicate the system even more and make it even harder to diagnose 
and fix.

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