Jdk 1.4.1 on arm or xscale
Title: Jdk 1.4.1 on arm or xscale Hi, There is a plan to port jdk1.4.1 on ARM or Xscale (Linux)? Yvan
Re: JVM and threads
Hello all, I also use Tomcat (v4.0.4), and I have run my webapp with a variety of JVMs in order to find which is best in terms of performance. It could be important to point that my Java code conforms to the 1.3 API specification, no 1.4-exclusive class or method is used. I found out that the best performing JVM on a single-processor Linux machine is Blackdown-1.3.1 with green threads and the OpenJIT compiler. Other JVMs I tried are: IBM v1.3.0 - 1.3.1, Sun v1.3.1 - 1.4.x It was a surprise for me to find out such a result, infact some benchmark classes I've done in order to measure pure processing power showed the IBM JDK as the best performer: nevertheless, when it comes to running my webapp under Tomcat, Blackdown 1.3.1 with green threads and OpenJIT makes it run _noticeably_ faster. Consequently, I surfed the net in order to find some command-line options to pass to the JVM in order to increase native threading scalability, but I didn't find anything useful. I looked at the NGPT home page, surfed the net and found some interesting benchmarks : http://www.opengroup.org/rtforum/jan2002/slides/linux/abt.pdf . At http://www.ibm.com/developerworks/oss/pthreads/, they say: "This release is fully suitable as a replacement for LinuxThreads by either a single user or group or an entire distribution." Does it mean that if I patch the kernel and install it on my system, my JVM will use it? I guess it's not so easy :-) Bye, Marco Trevisan -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: JVM and threads
Yup native threads doing blocking IO on linux is expensive. Things start looking progressively ugly from 50 connections upwards. If you move to NIO you will see a significant improvement in both stability/predictability and performance. What would make it easier for you to try the multiplexing IO feature instead? regards calvin Marco Trevisan wrote: > > Hello all, > > I also use Tomcat (v4.0.4), and I have run my webapp with a variety of > JVMs in order to find which is best in terms of performance. > It could be important to point that my Java code conforms to the 1.3 API > specification, no 1.4-exclusive class or method is used. > > I found out that the best performing JVM on a single-processor Linux > machine is Blackdown-1.3.1 with green threads and the OpenJIT compiler. > Other JVMs I tried are: IBM v1.3.0 - 1.3.1, Sun v1.3.1 - 1.4.x > > It was a surprise for me to find out such a result, infact some > benchmark classes I've done in order to measure pure processing power > showed the IBM JDK as the best performer: nevertheless, when it comes to > running my webapp under Tomcat, Blackdown 1.3.1 with green threads and > OpenJIT makes it run _noticeably_ faster. > > Consequently, I surfed the net in order to find some command-line > options to pass to the JVM in order to increase native threading > scalability, but I didn't find anything useful. > > I looked at the NGPT home page, surfed the net and found some > interesting benchmarks : > http://www.opengroup.org/rtforum/jan2002/slides/linux/abt.pdf . > > At http://www.ibm.com/developerworks/oss/pthreads/, they say: "This > release is fully suitable as a replacement for LinuxThreads by either a > single user or group or an entire distribution." > Does it mean that if I patch the kernel and install it on my system, my > JVM will use it? I guess it's not so easy :-) > > Bye, > Marco Trevisan > > -- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: JVM and threads
On Tue, Sep 03, 2002 at 10:03:15PM +0200, Marco Trevisan wrote: > I found out that the best performing JVM on a single-processor Linux > machine is Blackdown-1.3.1 with green threads and the OpenJIT compiler. > Other JVMs I tried are: IBM v1.3.0 - 1.3.1, Sun v1.3.1 - 1.4.x If there is any gain in speed it's most likely because of the context switching overhead of native threading (crossing kernel trap boundaries) verses green threading which runs within userspace (fast context switching). > It was a surprise for me to find out such a result, infact some > benchmark classes I've done in order to measure pure processing power > showed the IBM JDK as the best performer: nevertheless, when it comes to > running my webapp under Tomcat, Blackdown 1.3.1 with green threads and > OpenJIT makes it run _noticeably_ faster. OpenJIT is good stuff. :) > I looked at the NGPT home page, surfed the net and found some > interesting benchmarks : > http://www.opengroup.org/rtforum/jan2002/slides/linux/abt.pdf . There purpose is to build a highly scalable and complete pthreads system. LinuxThreads is missing a couple of things that are important to the Posix specification, namely proper signal handling. The HotSpot compiler code accounts for this brokeness with another signal handling layer within the internal thread management code... That's got to be addressed in the code before the threading system can run. > At http://www.ibm.com/developerworks/oss/pthreads/, they say: "This > release is fully suitable as a replacement for LinuxThreads by either a > single user or group or an entire distribution." > Does it mean that if I patch the kernel and install it on my system, my > JVM will use it? I guess it's not so easy :-) I believe what I've said to be accurate, but... If it emulates all the bad signal handling in Linux, then it might work. You can try it and report back to us. :) bill -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: JVM and threads
On Tue, Sep 03, 2002 at 10:03:15PM +0200, Marco Trevisan wrote: > I looked at the NGPT home page, surfed the net and found some > interesting benchmarks : > http://www.opengroup.org/rtforum/jan2002/slides/linux/abt.pdf . > > At http://www.ibm.com/developerworks/oss/pthreads/, they say: "This > release is fully suitable as a replacement for LinuxThreads by either a > single user or group or an entire distribution." > Does it mean that if I patch the kernel and install it on my system, my > JVM will use it? I guess it's not so easy :-) I haven't tried this library, but it claims to offer a pthreads API. So this might work for retrofitting an application (such as the JVM) that uses pthreads: LD_PRELOAD= <...command line...> For example: LD_PRELOAD=/usr/local/lib/libpth.so.1.4.1 java ... This is conjecture - I haven't tried it! It might not work, and there might be some intricate libc dependency problems on your system. But it's what I would try if I were to try it :-). Nathan Meyers [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
