[HARMONY-4705] [drlvm][jni] JNI transition uses ineffective TLS get

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0M6
• Component/s: DRLVM
• Patch Info: Patch Available
• Assignee: Gregory Shimansky
• Reporter: Aleksey Shipilev
• Created: 31/Aug/07 10:47
• Updated: 10/Apr/08 14:46
• Resolved: 10/Apr/08 14:46

Description

For now, JNI transition uses ineffective scheme of TLS getting - it is done via several recursive calls, finally reaching hythread_self().

The idea is to inline helper for TLS get instead of calling get_thread_ptr_stub(). Disassembly shows that 10 push/pops and 3 calls are completely eliminated there, keeping in mind that TLS get occurs at least 3 times on each JNI transition this give us a huge boost, eliminating up to 30 push/pops and 9 calls.

JNI microtest (calling several millions of empty JNI methods) testifies this:

$ ../../Builds/Harmony-clean/bin/java -cp . -Xmx128m -Xms128m nalog.nalog
iteration: 0 millis:8763
iteration: 1 millis:8722
iteration: 2 millis:8833

$ ../../Builds/Harmony-fastTLS-1/bin/java -cp . -Xmx128m -Xms128m nalog.nalog
iteration: 0 millis:6780
iteration: 1 millis:6689
iteration: 2 millis:6870

Issue Links

• blocks: HARMONY-4704 [drlvm][jni] JNI improvements
• is blocked by: HARMONY-4723 [drlvm][thread] hythread_self_helper wastes edx register on Linux/ia32