Actually it can, since run() method called only once per thread,
so even if run method is very hot it will never be substituted by
recompiled one.
Thanks,
Yuri
On 9/24/07, Weldon Washburn <[EMAIL PROTECTED]> wrote:
>
> On 9/24/07, Yuri Dolgov <[EMAIL PROTECTED]> wrote:
> > Hello,
> >
> > I've identified the most probable reason of the issue. It concerns to
> > gathering profiling information and absence of on stack replacement
> > mechanism.
>
> This is very interesting. Good work! I had no idea "on stack
> replacement" code could cause such problems.
>
>
> >
> > Currently profiling data is gathered even after it is not
> > needed any more for recompilation. And since there is no on stack
> > replacement mechanism there is overhead on collection profile data
> > till the end of the test. The problem could be solved by switching of
> > the profile counters after they are not useful.
> >
> > BTW I'm using pretty fresh version of Harmony (release build) and
> > can reproduce Cyang's problem.
> >
> > Thanks,
> > Yuri
> >
> > On 9/24/07, Weldon Washburn <[EMAIL PROTECTED]> wrote:
> > >
> > > Cyang, Yuri,
> > >
> > > I have committed several threading patches since M2 was released.
> > > These threading patches might impact the performance of your test
> > > below. Are you using release build or debug build?
> > >
> > > I noticed your test uses Thread.join(). There are several known bugs
> > > in Thread.join() that we hope to fix shortly. We are working on the
> > > list of threading problems described in April 2 email called,
> > > "[drlvm][threading] a list of design/development issues that need
> > > coordination with the [general] "M1" map". In particular we hope to
> > > have, "Varying Mutexes Protect Different Parts of Thread State, Each
> > > Thread Has Its Own Mutex" done in the next few months. In other
> > > words, before M4 or M5 is released. This project (also called Thread
> > > State Transition Project) intends to fix known Thread.join() problems.
> > >
> > > If you have the time, please try again with what is in svn HEAD. Or
> > > perhaps wait until M3 is released shortly.
> > >
> > > On 9/24/07, cyang.cq <[EMAIL PROTECTED]> wrote:
> > > > Hi, all
> > > > The scalability of the program below is surprising on M2.
> > > > This program only starts several threads to share the work
> > > > of doing a number of additions.
> > > >
> > > > MT.java:
> > > >
> > > > public class MT extends Thread{
> > > >
> > > > static long result = 0;
> > > > long len = 0;
> > > > public MT(long len){
> > > > this.len = len;
> > > > }
> > > >
> > > > public void run(){
> > > > long total = 0;
> > > > for(long i = 0; i < len; ++i){
> > > > total += 1;
> > > > }
> > > > result = total;
> > > > }
> > > >
> > > > public static void main(String[] args) throws InterruptedException
> {
> > > > long totalWork = Long.parseLong(args[0]);
> > > > int numThreads = Integer.parseInt(args[1]);
> > > >
> > > > long work = totalWork / numThreads;
> > > >
> > > > MT[] v = new MT[numThreads];
> > > > for(int i = 0; i < numThreads; ++i){
> > > > v[i] = new MT(work);
> > > > }
> > > >
> > > > long start = System.currentTimeMillis();
> > > > for(int i = 0; i < numThreads; ++i){
> > > > v[i].start();
> > > > }
> > > > for(int i = 0; i < numThreads; ++i){
> > > > v[i].join();
> > > > }
> > > > long dur = System.currentTimeMillis() - start;
> > > >
> > > > System.out.println("Total time: " + dur);
> > > > }
> > > >
> > > > }
> > > >
> > > > Run it on 5.0M2:
> > > > CMD OUTPUT
> > > > java MT 9000000000 1 Total time: 411325
> > > > java MT 9000000000 2 Total time: 1052861
> > > > java MT 9000000000 4 Total time: 915545
> > > > java MT 9000000000 8 Total time: 589672
> > > > java MT 9000000000 12 Total time: 678815
> > > > java MT 9000000000 16 Total time: 621097
> > > >
> > > >
> > > > Run it on sun jdk 1.5.0_08:
> > > > CMD OUTPUT
> > > > java MT 9000000000 1 Total time: 10356
> > > > java MT 9000000000 2 Total time: 5182
> > > > java MT 9000000000 4 Total time: 2601
> > > > java MT 9000000000 8 Total time: 1453
> > > > java MT 9000000000 12 Total time: 1004
> > > > java MT 9000000000 16 Total time: 782
> > > >
> > > >
> > > >
> > > > My configuration is:
> > > > OS: Red Hat Enterprise Linux AS release 4 (Nahant Update 4)
> > > > Kernel 2.6.9-42.ELlargesmp on an x86_64
> > > > CPU: 8 X Dual-Core AMD Opteron 2.6G
> > > > Mem: 16G
> > > > drlvm: Apache Harmony 5.0M2 JRE for 32-bit Linux
> > > > for systems with libstdc++.so.5
> > > > sun jdk: jdk-1_5_0_08-linux-i586
> > > >
> > > >
> > > > Any suggestions? Have this been fixed already since M2?
> > > >
> > > > Thanks in advance.
> > >
> > >
> > > --
> > > Weldon Washburn
> > >
> >
>
>
> --
> Weldon Washburn
>
