[pypy-commit] stmgc c7-refactor: Rename "stm_current_transaction_t" into "stm_creation_marker_t".

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: c7-refactor
Changeset: r729:508eed0d9371
Date: 2014-02-14 14:22 +0100
http://bitbucket.org/pypy/stmgc/changeset/508eed0d9371/

Log:	Rename "stm_current_transaction_t" into "stm_creation_marker_t".

diff --git a/c7/stm/core.h b/c7/stm/core.h
--- a/c7/stm/core.h
+++ b/c7/stm/core.h
@@ -18,10 +18,13 @@
 #define FIRST_OBJECT_PAGE     ((READMARKER_END + 4095) / 4096UL)
 #define FIRST_NURSERY_PAGE    FIRST_OBJECT_PAGE
 #define END_NURSERY_PAGE      (FIRST_NURSERY_PAGE + NB_NURSERY_PAGES)
+
 #define READMARKER_START      ((FIRST_OBJECT_PAGE * 4096UL) >> 4)
 #define FIRST_READMARKER_PAGE (READMARKER_START / 4096UL)
 #define NB_READMARKER_PAGES   (FIRST_OBJECT_PAGE - FIRST_READMARKER_PAGE)
 
+#define CURTRANS_START        ((FIRST_OBJECT_PAGE * 4096UL) >> 8)
+
 
 enum {
     /* this flag is not set on most objects.  when stm_write() is called
diff --git a/c7/stm/nursery.c b/c7/stm/nursery.c
--- a/c7/stm/nursery.c
+++ b/c7/stm/nursery.c
@@ -17,10 +17,10 @@
 
 /* if objects are larger than this limit but smaller than LARGE_OBJECT,
    then they might be allocted outside sections but still in the nursery. */
-#define MEDIUM_OBJECT         (9*1024)
+#define MEDIUM_OBJECT         (8*1024)
 
 /* size in bytes of the alignment of any section requested */
-#define NURSERY_ALIGNMENT     64
+#define NURSERY_ALIGNMENT     256
 
 /************************************************************/
 
diff --git a/c7/stm/setup.c b/c7/stm/setup.c
--- a/c7/stm/setup.c
+++ b/c7/stm/setup.c
@@ -21,6 +21,10 @@
     assert(READMARKER_START < READMARKER_END);
     assert(READMARKER_END <= 4096UL * FIRST_OBJECT_PAGE);
     assert(FIRST_OBJECT_PAGE < NB_PAGES);
+    assert(CURTRANS_START >= 8192);
+    assert((NB_PAGES * 4096UL) >> 8 <= (FIRST_OBJECT_PAGE * 4096UL) >> 4);
+    assert((END_NURSERY_PAGE * 4096UL) >> 8 <=
+           (FIRST_READMARKER_PAGE * 4096UL));
 
     stm_object_pages = mmap(NULL, TOTAL_MEMORY,
                             PROT_READ | PROT_WRITE,
@@ -59,13 +63,19 @@
        long time for each page. */
     pages_initialize_shared(FIRST_NURSERY_PAGE, NB_NURSERY_PAGES);
 
+    /* The read markers are initially zero, which is correct:
+       STM_SEGMENT->transaction_read_version never contains zero,
+       so a null read marker means "not read" whatever the
+       current transaction_read_version is.
+
+       The creation markers are initially zero, which is correct:
+       it means "objects of this group of 256 bytes have not been
+       allocated by the current transaction."
+    */
+
     setup_sync();
     setup_nursery();
     setup_gcpage();
-
-#if 0
-    stm_largemalloc_init(heap, HEAP_PAGES * 4096UL);
-#endif
 }
 
 void stm_teardown(void)
diff --git a/c7/stmgc.h b/c7/stmgc.h
--- a/c7/stmgc.h
+++ b/c7/stmgc.h
@@ -33,16 +33,27 @@
 typedef TLPREFIX struct object_s object_t;
 typedef TLPREFIX struct stm_segment_info_s stm_segment_info_t;
 typedef TLPREFIX struct stm_read_marker_s stm_read_marker_t;
-typedef TLPREFIX struct stm_current_transaction_s stm_current_transaction_t;
+typedef TLPREFIX struct stm_creation_marker_s stm_creation_marker_t;
 typedef TLPREFIX char stm_char;
 typedef void* stm_jmpbuf_t[5];  /* for use with __builtin_setjmp() */
 
 struct stm_read_marker_s {
+    /* In every segment, every object has a corresponding read marker.
+       We assume that objects are at least 16 bytes long, and use
+       their address divided by 16.  The read marker is equal to
+       'STM_SEGMENT->transaction_read_version' if and only if the
+       object was read in the current transaction. */
     uint8_t rm;
 };
 
-struct stm_current_transaction_s {
-    uint8_t ct;
+struct stm_creation_marker_s {
+    /* In addition to read markers, every group of 256 bytes has one
+       extra byte, the creation marker, located at the address divided
+       by 256.  The creation marker is either 0xff if all objects in
+       this group come have been allocated by the current transaction,
+       or 0x00 if none of them have been.  Groups cannot contain a
+       mixture of both. */
+    uint8_t cm;
 };
 
 struct stm_segment_info_s {
@@ -125,9 +136,9 @@
 {
     /* this is:
            'if (ct == 0 && (stm_flags & WRITE_BARRIER_CALLED) == 0)'
-         assuming that 'ct' is either 0 (no, not current transaction)
-           or 0xff (yes) */
-    if (UNLIKELY(!(((stm_current_transaction_t *)(((uintptr_t)obj) >> 8)->ct |
+         assuming that 'cm' is either 0 (not created in current transaction)
+                                or 0xff (created in current transaction) */
+    if (UNLIKELY(!(((stm_creation_marker_t *)(((uintptr_t)obj) >> 8)->cm |
                     obj->stm_flags) & _STM_GCFLAG_WRITE_BARRIER_CALLED)))
         _stm_write_slowpath(obj);
 }