Return-Path: Delivered-To: apmail-harmony-dev-archive@www.apache.org Received: (qmail 58922 invoked from network); 24 May 2007 05:58:37 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.2) by minotaur.apache.org with SMTP; 24 May 2007 05:58:37 -0000 Received: (qmail 66466 invoked by uid 500); 24 May 2007 05:58:41 -0000 Delivered-To: apmail-harmony-dev-archive@harmony.apache.org Received: (qmail 66428 invoked by uid 500); 24 May 2007 05:58:41 -0000 Mailing-List: contact dev-help@harmony.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@harmony.apache.org Delivered-To: mailing list dev@harmony.apache.org Received: (qmail 66419 invoked by uid 99); 24 May 2007 05:58:41 -0000 Received: from herse.apache.org (HELO herse.apache.org) (140.211.11.133) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 23 May 2007 22:58:41 -0700 X-ASF-Spam-Status: No, hits=2.0 required=10.0 tests=HTML_MESSAGE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (herse.apache.org: domain of mike.fursov@gmail.com designates 64.233.166.177 as permitted sender) Received: from [64.233.166.177] (HELO py-out-1112.google.com) (64.233.166.177) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 23 May 2007 22:58:34 -0700 Received: by py-out-1112.google.com with SMTP id a29so733486pyi for ; Wed, 23 May 2007 22:58:13 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=pREFyE2G/ODL9GU7dMhPcXCrq36oiCYf/g7xEp1BAb82qnX6YGOV5NjdJLX+l11HBxWqU+uirnvAWVnWQNQ7RaStvbmGmFtYnNmhoFiEcGb9FCDEhxcrQiGPu90OeYz2nQNHfFXjrULS3IAnkGsAllEbdDhq5LmZet2+JQgqMM4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=dfF0pe1EyivdCThNYeIBzCpNgWwr0eIWEDvi1wUjS1J41A9V1rmllpw6I26DW8/WeiLWmhIMy0RCPQUu8HTOx0g9A8BQ0Tp+9oglvgT5epbloWGdJeP4me+nHGJlEEuTBzUgra89ifEUbGx1iu3cqYVCpQ94P+xWk+2hgvpASLU= Received: by 10.35.111.14 with SMTP id o14mr1611608pym.1179986293506; Wed, 23 May 2007 22:58:13 -0700 (PDT) Received: by 10.35.36.9 with HTTP; Wed, 23 May 2007 22:58:13 -0700 (PDT) Message-ID: Date: Thu, 24 May 2007 12:58:13 +0700 From: "Mikhail Fursov" To: dev@harmony.apache.org Subject: Re: [jira] Updated: (HARMONY-2092) [drlvm][jit] Harmony works with volatile variables incorrectly In-Reply-To: <9623c9a50705230550s43d5a766u1fc75658885dc8b@mail.gmail.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_63885_26689511.1179986293433" References: <17006127.1179913816525.JavaMail.jira@brutus> <9623c9a50705230421ka79d039s1618eaf48da090a6@mail.gmail.com> <9623c9a50705230550s43d5a766u1fc75658885dc8b@mail.gmail.com> X-Virus-Checked: Checked by ClamAV on apache.org ------=_Part_63885_26689511.1179986293433 Content-Type: text/plain; charset=ISO-2022-JP; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Xiao-Feng, Jitrino on IA32 platform splits every 64-bit integer into two 32-bit values and every store/load of 64bit integer is done with 2 separate store/loads of 32-bit ones.Before using locks we must have single 64bit store/load instruction. When we have it - lock prefix won't be needed at all (AFAIU) You point about compatibility with no-SSE platform is good. George, what do you think about FISTP to store 64-bit integers to memory? On 5/23/07, Xiao-Feng Li wrote: > > On 5/23/07, Mikhail Fursov wrote: > > On 5/23/07, Xiao-Feng Li wrote: > > > > > > I had a question in the JIRA about this issue: why don't we use "lock" > > > prefix for the atomic access? > > > > > > Lock prefix will cause significant performance degradation. For example, > > some time ago, when our monenter implementation always used locks the > > inlining of this helper gave no benefit at all. The removal of lock > without > > inlining gave a real benefit but was illegal. > > Ｍｉｋｈａｉｌ, actually I was working on synchronization for a pretty long > time, so the "lock" prefix implication to performance is well > understood. In my understanding, volatile long is quite different from > Java monitor. I personally don't believe that to use "lock" prefix for > volatile long can cause any visible performance issue in real > workloads, if it doesn't bring performance improvement. (Probably JIT > can do a good job here to optimize the excessive "lock" prefixes if > the volatile long variable really shows performance issue, although > it's unlikely to happen in real workloads.) > > My concern is the 8-byte object alignment requirement if we use > current solution. It requires to change the class loader and object > arrangement in heap. For example, do we have any performance study on > its implication to SPECs? Probably the 8-byte alignment would > ultimately be needed for Harmony, but there is a methodology issue > here: Currently the problem with volatile long is its correctness, > instead of its performance. We don't need consider too much about the > performance issue if we can achieve the correctness relatively > trivially and quickly (by simply emitting a "lock" prefix). Then we > can check if the performance is indeed an issue. We still keep the > optimization opportunities, and it's not late to implement current > solution after we have a good understanding in the issue. > > These are just my cents, for your reference. :-) > > > AFAIK we do not have problems with volatile int32/int16/int8 types today > on > > 32bit PC. If this is true we can try to handle int64 values using 64bit > > registers without locks too. > > Yes, as I described above, it's good to have the try, but we need > consider more. For example, do we know if it will introduce any > portability issue? > > Thanks, > xiaofeng > > > > > > > Thanks, > > > xiaofeng > > > > > > On 5/23/07, George Timoshenko (JIRA) < jira@apache.org> wrote: > > > > > > > > [ > https://issues.apache.org/jira/browse/HARMONY-2092?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel > > > ] > > > > > > > > George Timoshenko updated HARMONY-2092: > > > > --------------------------------------- > > > > > > > > Attachment: HARMONY-2092-regression_test.patch > > > > > > > > regression test > > > > based on the testcase by Mikhail Fursov > > > > > > > > > [drlvm][jit] Harmony works with volatile variables incorrectly > > > > > -------------------------------------------------------------- > > > > > > > > > > Key: HARMONY-2092 > > > > > URL: > > > https://issues.apache.org/jira/browse/HARMONY-2092 > > > > > Project: Harmony > > > > > Issue Type: Bug > > > > > Components: DRLVM > > > > > Environment: Windows and Linux > > > > > Reporter: Vera Petrashkova > > > > > Assigned To: weldon washburn > > > > > Attachments: classloader_and_gc_quick_fix.diff, > > > HARMONY-2092-regression_test.patch, HARMONY-2092.patch, > volatileTest.zip > > > > > > > > > > > > > > > When Long_MAX_VALUE or Long.MIN_VALUE should be assigned to > volatile > > > variable then > > > > > VM works incorrectly. > > > > > Code for reproducing: > > > > > ------------------volatileTest.java----------------- > > > > > public class volatileTest { > > > > > public static int delay = 5000; > > > > > private boolean interruptFlag = false; > > > > > long hi; > > > > > long lo; > > > > > volatile long v; > > > > > public static void main(String [] args ) { > > > > > int maxI = 20; > > > > > for (int i = 0; i < maxI; i++) { > > > > > int t = new volatileTest().test(delay); > > > > > System.out.println((t == 104 ? "Test passed: ": "Test > > > failed: ") > > > > > + t + " (step: " + i + ")"); > > > > > } > > > > > } > > > > > public synchronized void interrupt() { > > > > > interruptFlag = true; > > > > > } > > > > > public synchronized boolean interrupted() { > > > > > return interruptFlag; > > > > > } > > > > > public volatileTest() { > > > > > super(); > > > > > hi = Long.MAX_VALUE; > > > > > lo = Long.MIN_VALUE; > > > > > v = hi; > > > > > } > > > > > public int test(int delay) { > > > > > boolean passed = true; > > > > > Thread_1_class t1 = new Thread_1_class(this); > > > > > Thread_2_class t2 = new Thread_2_class(this); > > > > > Interruptor killer = new Interruptor(this, delay); > > > > > try { > > > > > t1.start(); > > > > > t2.start(); > > > > > killer.start(); > > > > > > > > > > while (!interrupted()) { > > > > > Thread.yield(); > > > > > long v3 = v; > > > > > if (v3 != hi && v3 != lo) { > > > > > System.out.println(v3+" "+hi +" "+lo); > > > > > passed = false; > > > > > break; > > > > > } > > > > > } > > > > > t1.interrupt(); > > > > > t2.interrupt(); > > > > > return passed ? 104 : 105; > > > > > } catch (Throwable e) { > > > > > e.printStackTrace(); > > > > > return 106; > > > > > } > > > > > } > > > > > } > > > > > class Thread_1_class extends Thread { > > > > > volatileTest thh; > > > > > public Thread_1_class (volatileTest t) { > > > > > super(); > > > > > thh = t; > > > > > } > > > > > public void run() { > > > > > while (!isInterrupted()) { > > > > > thh.v = thh.lo; > > > > > thh.v = thh.hi; > > > > > } > > > > > } > > > > > } > > > > > class Thread_2_class extends Thread { > > > > > volatileTest thh; > > > > > public Thread_2_class (volatileTest t) { > > > > > super(); > > > > > thh = t; > > > > > } > > > > > public void run() { > > > > > while (!isInterrupted()) { > > > > > thh.v = thh.hi; > > > > > thh.v = thh.lo; > > > > > } > > > > > } > > > > > } > > > > > class Interruptor extends Thread { > > > > > volatileTest t; > > > > > int delay; > > > > > public Interruptor(volatileTest t, int delay) { > > > > > this.t = t; > > > > > this.delay = delay; > > > > > } > > > > > public void run() { > > > > > try { > > > > > Thread.sleep(delay); > > > > > } catch (InterruptedException e) { > > > > > } > > > > > t.interrupt(); > > > > > } > > > > > } > > > > > ---------------------------- > > > > > Output on RI: > > > > > ================ > > > > > java version " 1.5.0_06" > > > > > Java(TM) 2 Runtime Environment, Standard Edition (build > 1.5.0_06-b05) > > > > > Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode) > > > > > Test passed: 104 (step: 0) > > > > > Test passed: 104 (step: 1) > > > > > Test passed: 104 (step: 2) > > > > > Test passed: 104 (step: 3) > > > > > Test passed: 104 (step: 4) > > > > > Test passed: 104 (step: 5) > > > > > Test passed: 104 (step: 6) > > > > > Test passed: 104 (step: 7) > > > > > Test passed: 104 (step: 8) > > > > > Test passed: 104 (step: 9) > > > > > Test passed: 104 (step: 10) > > > > > Test passed: 104 (step: 11) > > > > > Test passed: 104 (step: 12) > > > > > Test passed: 104 (step: 13) > > > > > Test passed: 104 (step: 14) > > > > > Test passed: 104 (step: 15) > > > > > Test passed: 104 (step: 16) > > > > > Test passed: 104 (step: 17) > > > > > Test passed: 104 (step: 18) > > > > > Test passed: 104 (step: 19) > > > > > Output on Harmony: > > > > > ==================== > > > > > Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache > Software > > > Foundation or its licensors, as applicable. > > > > > java version " 1.5.0" > > > > > pre-alpha : not complete or compatible > > > > > svn = r471468, (Nov 7 2006), Windows/ia32/msvc 1310, release > build > > > > > http://incubator.apache.org/harmony > > > > > Test passed: 104 (step: 0) > > > > > Test passed: 104 (step: 1) > > > > > Test passed: 104 (step: 2) > > > > > Test passed: 104 (step: 3) > > > > > Test passed: 104 (step: 4) > > > > > Test passed: 104 (step: 5) > > > > > Test passed: 104 (step: 6) > > > > > Test passed: 104 (step: 7) > > > > > Test passed: 104 (step: 8) > > > > > Test passed: 104 (step: 9) > > > > > Test passed: 104 (step: 10) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 11) > > > > > Test passed: 104 (step: 12) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 13) > > > > > Test passed: 104 (step: 14) > > > > > Test passed: 104 (step: 15) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 16) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 17) > > > > > Test passed: 104 (step: 18) > > > > > Test passed: 104 (step: 19) > > > > > Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache > Software > > > Foundation or its licensors, as applicable. > > > > > java version "1.5.0" > > > > > pre-alpha : not complete or compatible > > > > > svn = r471468, (Nov 7 2006), Linux/ia32/gcc 3.3.3, release build > > > > > http://incubator.apache.org/harmony > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 0) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 1) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 2) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 3) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 4) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 5) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 6) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 7) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 8) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 9) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 10) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 11) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 12) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 13) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 14) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 15) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 16) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 17) > > > > > -9223372032559808513 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 18) > > > > > 9223372032559808512 9223372036854775807 -9223372036854775808 > > > > > Test failed: 105 (step: 19) > > > > > This bug is reproducible on Jitrino (JET/OPT) and on interpreter: > > > > > java -cp . volatileTest > > > > > java -cp . -Xint volatileTest > > > > > java -cp . -Xem:opt volatileTest > > > > > > > > -- > > > > This message is automatically generated by JIRA. > > > > - > > > > You can reply to this email to add a comment to the issue online. > > > > > > > > > > > > > > > > > -- > > > http://xiao-feng.blogspot.com > > > > > > > > > > > -- > > Mikhail Fursov > > > > > -- > http://xiao-feng.blogspot.com > -- Mikhail Fursov ------=_Part_63885_26689511.1179986293433--