4 ms·

All I know is that we once had to temporarily move a cvs repository from a brand new and crazy expensive pSeries 660 (?) running AIX to a really old and retired

by kpil 11y ago

All I know is that we once had to temporarily move a cvs repository from a brand new and crazy expensive pSeries 660 (?) running AIX to a really old and retired Pentium III laptop that we had found in a drawer and installed linux on. This was almost 15 years ago, but the laptop was easily 3 years old at that time - possibly older and positively not a 4 or 6 core server with gigabytes of ram and a big SCSI raid array. The linux laptop was then connected to a well used wan-connection in another location, and we tunneled to it using ssh, instead of just accessing it on the 100 mbit lan, and sent out an apologetic email notifying the developers that things would be really slow until we had sorted things out with the AIX systems. ( They had to be moved to another location.) We found to our surprise that the throughput dramatically improved and checkout times where reduced to almost nothing compared to the AIX machine it usually ran on. Now, maybe CVS is an exceptionally bad workload for AIX or something, but I doubt that it's an uncommon workload. AIX might possibly scale to more CPUs efficiently, but it was a clear disappointment nevertheless.

travem 11y ago
I wonder if this may be attributable to the difference between a CPU bound versus an IO bound workload? I imagine CVS is doing a fair amount of IO, which on a laptop with local disk (and no competing workloads driving IO) may be able to handle pretty effectively.
- kpil 11y ago
  There were no competing workload and no virtualization on the AIX either. We didn't need it (yet) for other things.
jacquesm 11y ago
One possible effect of your email may have been that people simply did not attempt to check in their work until you had 'sorted things out'. That way you'd have reduced load and therefore a snappier system.
- kpil 11y ago
  No, we stayed on the laptop. It was eventually moved from the other site to a proper server room, still with a sticky note on it. We might have forgotten to mention this fact to some people though...
  - kjs3 11y ago
    So going to production for you is moving a laptop to the datacenter? Yeah. Bullshit.
    - kpil 11y ago
      What? No? CVS is a version control system. We kept (a copy of ) the source in the laptop. The actual system we developed was running in machines guarded by hordes of sysadmins grumped up to the proper level, possibly even employed by IBM.
mattzito 11y ago
It's entirely possible back in those days that you had a tiny LPAR (VM) for your CVS data on a big pSeries box that was shared with a bunch of other resources. On top of that, it wasn't uncommon to connect those tiny LPARs to shared storage RAID arrays with hundreds of machines on the same array, and allocate them a tiny chunk of two or three disks, and deal with all the contention there. During that time period, I worked for a hot second at EMC, and was always fascinated to see these types of configurations - where it was very clear you could get MUCH better price/performance by buying Linux pizza boxes and connecting them to local storage - but back in those days it was not acceptable at big companies to do that. On the flip side, those pSeries and high-end Sun boxes screamed when they were optimized for high I/O and high performance workloads. 15 years ago, and you'd see clusters of these pSeries boxes processing 400k-500k writes/second and up on Oracle and DB2. Truly impressive stuff for 2000 & 2001.
- kpil 11y ago
  Hm, no not really. The cvs daemon had the whole machine for itself.
  - kjs3 11y ago
    Hm, bullshit. Seriously.
    - kpil 11y ago
      Seriously not bullshit. To be fair it can be due to a crappy cvs port or related to something that cvs do that does not work well on the non-unixy memmory mapped io model on AIX.
      - kjs3 11y ago
        I've used AIX since it ran on the RT. I've used CVS since a buddy said "hey...this guy has some shell scripts that work better than SCCS" (i.e. the late 80s). I've done OS performance analysis for decades. I'm quite clear on how those boxes perform. Quit doubling down on the bullshit that an unloaded 660 with server class I/O is outperformed by a mobile P3 cramming data down a laptop IDE bus. It never happened. What happened is something like what mattzito described and you just have no idea how real systems are deployed and managed.

by kpil 11y ago

travem 11y ago

I wonder if this may be attributable to the difference between a CPU bound versus an IO bound workload? I imagine CVS is doing a fair amount of IO, which on a laptop with local disk (and no competing workloads driving IO) may be able to handle pretty effectively.

kpil 11y ago
There were no competing workload and no virtualization on the AIX either. We didn't need it (yet) for other things.

jacquesm 11y ago

One possible effect of your email may have been that people simply did not attempt to check in their work until you had 'sorted things out'. That way you'd have reduced load and therefore a snappier system.

kpil 11y ago
No, we stayed on the laptop. It was eventually moved from the other site to a proper server room, still with a sticky note on it. We might have forgotten to mention this fact to some people though...
- kjs3 11y ago
  So going to production for you is moving a laptop to the datacenter? Yeah. Bullshit.
  - kpil 11y ago
    What? No? CVS is a version control system. We kept (a copy of ) the source in the laptop. The actual system we developed was running in machines guarded by hordes of sysadmins grumped up to the proper level, possibly even employed by IBM.

mattzito 11y ago

It's entirely possible back in those days that you had a tiny LPAR (VM) for your CVS data on a big pSeries box that was shared with a bunch of other resources. On top of that, it wasn't uncommon to connect those tiny LPARs to shared storage RAID arrays with hundreds of machines on the same array, and allocate them a tiny chunk of two or three disks, and deal with all the contention there. During that time period, I worked for a hot second at EMC, and was always fascinated to see these types of configurations - where it was very clear you could get MUCH better price/performance by buying Linux pizza boxes and connecting them to local storage - but back in those days it was not acceptable at big companies to do that. On the flip side, those pSeries and high-end Sun boxes screamed when they were optimized for high I/O and high performance workloads. 15 years ago, and you'd see clusters of these pSeries boxes processing 400k-500k writes/second and up on Oracle and DB2. Truly impressive stuff for 2000 & 2001.

kpil 11y ago
Hm, no not really. The cvs daemon had the whole machine for itself.
- kjs3 11y ago
  Hm, bullshit. Seriously.
  - kpil 11y ago
    Seriously not bullshit. To be fair it can be due to a crappy cvs port or related to something that cvs do that does not work well on the non-unixy memmory mapped io model on AIX.
    - kjs3 11y ago
      I've used AIX since it ran on the RT. I've used CVS since a buddy said "hey...this guy has some shell scripts that work better than SCCS" (i.e. the late 80s). I've done OS performance analysis for decades. I'm quite clear on how those boxes perform. Quit doubling down on the bullshit that an unloaded 660 with server class I/O is outperformed by a mobile P3 cramming data down a laptop IDE bus. It never happened. What happened is something like what mattzito described and you just have no idea how real systems are deployed and managed.