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* [trans-mem] Move state from gtm_thread to gtm_transaction
@ 2011-08-03 11:05 Torvald Riegel
  2011-08-04 15:43 ` Richard Henderson
  0 siblings, 1 reply; 7+ messages in thread
From: Torvald Riegel @ 2011-08-03 11:05 UTC (permalink / raw)
  To: GCC Patches; +Cc: Aldy Hernandez, Richard Henderson

[-- Attachment #1: Type: text/plain, Size: 501 bytes --]

patch3:
After the previous change to flat nesting by default, checkpoints, and
thus having only a single gtm_transaction object per thread, we can move
the local_tid field to gtm_transaction too. As a result, we don't have
to access gtm_thread in GTM_begin_transaction anymore.

patch4:
A small fix that adds a missing set-up call for gtm_thread. And a
matching test case, which tests that the functions in query.cc work even
if no transaction has been executed so far in this thread.

OK for branch?

[-- Attachment #2: patch3 --]
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commit 33c3c869c7cb986bcca3f3f44b0412278e880a82
Author: Torvald Riegel <triegel@redhat.com>
Date:   Fri Jul 29 16:09:05 2011 +0200

    Move local_tid from gtm_thread to gtm_transaction.
    
    	* config/generic/tls.h (gtm_thread): Move local_tid from here ...
    	* libitm_i.h (local_tid): ... to here.
    	* beginend.cc (GTM::gtm_transaction::begin_transaction): Same.
    	(GTM::gtm_transaction::operator new): Set up gtm_thread if necessary.

diff --git a/libitm/beginend.cc b/libitm/beginend.cc
index d336d60..a16c3f9 100644
--- a/libitm/beginend.cc
+++ b/libitm/beginend.cc
@@ -43,7 +43,7 @@ static _ITM_transactionId_t global_tid;
 void *
 GTM::gtm_transaction::operator new (size_t s)
 {
-  gtm_thread *thr = gtm_thr ();
+  gtm_thread *thr = setup_gtm_thr ();
   void *tx;
 
   assert(s == sizeof(gtm_transaction));
@@ -112,8 +112,6 @@ GTM::gtm_transaction::begin_transaction (uint32_t prop, const gtm_jmpbuf *jb)
   if (unlikely(prop & pr_undoLogCode))
     GTM_fatal("pr_undoLogCode not supported");
 
-  gtm_thread *thr = setup_gtm_thr ();
-
   tx = gtm_tx();
   if (tx == NULL)
     {
@@ -214,18 +212,18 @@ GTM::gtm_transaction::begin_transaction (uint32_t prop, const gtm_jmpbuf *jb)
 
   // As long as we have not exhausted a previously allocated block of TIDs,
   // we can avoid an atomic operation on a shared cacheline.
-  if (thr->local_tid & (tid_block_size - 1))
-    tx->id = thr->local_tid++;
+  if (tx->local_tid & (tid_block_size - 1))
+    tx->id = tx->local_tid++;
   else
     {
 #ifdef HAVE_64BIT_SYNC_BUILTINS
       tx->id = __sync_add_and_fetch (&global_tid, tid_block_size);
-      thr->local_tid = tx->id + 1;
+      tx->local_tid = tx->id + 1;
 #else
       pthread_mutex_lock (&global_tid_lock);
       global_tid += tid_block_size;
       tx->id = global_tid;
-      thr->local_tid = tx->id + 1;
+      tx->local_tid = tx->id + 1;
       pthread_mutex_unlock (&global_tid_lock);
 #endif
     }
diff --git a/libitm/config/generic/tls.h b/libitm/config/generic/tls.h
index 82d7c66..8a39b80 100644
--- a/libitm/config/generic/tls.h
+++ b/libitm/config/generic/tls.h
@@ -50,12 +50,6 @@ struct gtm_thread
   void *free_tx[MAX_FREE_TX];
   unsigned free_tx_idx, free_tx_count;
 
-  // In order to reduce cacheline contention on global_tid during
-  // beginTransaction, we allocate a block of 2**N ids to the thread
-  // all at once.  This number is the next value to be allocated from
-  // the block, or 0 % 2**N if no such block is allocated.
-  _ITM_transactionId_t local_tid;
-
   // The value returned by _ITM_getThreadnum to identify this thread.
   // ??? At present, this is densely allocated beginning with 1 and
   // we don't bother filling in this value until it is requested.
diff --git a/libitm/libitm_i.h b/libitm/libitm_i.h
index 97f535a..7d475be 100644
--- a/libitm/libitm_i.h
+++ b/libitm/libitm_i.h
@@ -168,6 +168,12 @@ struct gtm_transaction
   // A bitmask of the above.
   uint32_t state;
 
+  // In order to reduce cacheline contention on global_tid during
+  // beginTransaction, we allocate a block of 2**N ids to the thread
+  // all at once.  This number is the next value to be allocated from
+  // the block, or 0 % 2**N if no such block is allocated.
+  _ITM_transactionId_t local_tid;
+
   // Data used by eh_cpp.c for managing exceptions within the transaction.
   uint32_t cxa_catch_count;
   void *cxa_unthrown;

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commit 22c19978ba11c0ae0321449d8809260ab5f97741
Author: Torvald Riegel <triegel@redhat.com>
Date:   Fri Jul 29 16:19:41 2011 +0200

    Fix missing setup of gtm_thread if no transaction has run yet.
    
    	* query.cc (_ITM_getThreadnum): Set up gtm_thread if necessary.
    	* testsuite/libitm.c/notx.c: New file.

diff --git a/libitm/query.cc b/libitm/query.cc
index 9a95211..02f1813 100644
--- a/libitm/query.cc
+++ b/libitm/query.cc
@@ -67,7 +67,7 @@ int ITM_REGPARM
 _ITM_getThreadnum (void)
 {
   static int global_num;
-  struct gtm_thread *thr = gtm_thr();
+  struct gtm_thread *thr = setup_gtm_thr();
   int num = thr->thread_num;
 
   if (num == 0)
diff --git a/libitm/testsuite/libitm.c/notx.c b/libitm/testsuite/libitm.c/notx.c
new file mode 100644
index 0000000..92ae3e1
--- /dev/null
+++ b/libitm/testsuite/libitm.c/notx.c
@@ -0,0 +1,36 @@
+/* These tests all check whether initialization happens properly even if no
+   transaction has been used in the current thread yet.  */
+#include <stdlib.h>
+#include <pthread.h>
+#include <libitm.h>
+
+static void *test1 (void *dummy __attribute__((unused)))
+{
+  if (_ITM_inTransaction() != outsideTransaction)
+    abort();
+  return NULL;
+}
+
+static void *test2 (void *dummy __attribute__((unused)))
+{
+  if (_ITM_getTransactionId() != _ITM_noTransactionId)
+    abort();
+  return NULL;
+}
+
+
+int main()
+{
+  pthread_t thread;
+
+  if (_ITM_getThreadnum() != 1)
+    abort();
+
+  pthread_create(&thread, NULL, test1, NULL);
+  pthread_join(thread, NULL);
+
+  pthread_create(&thread, NULL, test2, NULL);
+  pthread_join(thread, NULL);
+
+  return 0;
+}

^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2011-08-05 23:45 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-08-03 11:05 [trans-mem] Move state from gtm_thread to gtm_transaction Torvald Riegel
2011-08-04 15:43 ` Richard Henderson
2011-08-04 16:23   ` Torvald Riegel
2011-08-04 18:55     ` Richard Henderson
2011-08-04 19:24       ` Torvald Riegel
2011-08-04 19:35         ` Richard Henderson
2011-08-06  4:29           ` Torvald Riegel

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