fixup

NEWS.md

@@ -14,9 +14,6 @@ Language changes
 
 Compiler/Runtime improvements
 -----------------------------
-* Updated GC heuristics to count allocated pages instead of individual objects ([#50144]).
-* A new `LazyLibrary` type is exported from `Libdl` for use in building chained lazy library
-  loads, primarily to be used within JLLs ([#50074]).
 
 Command-line option changes
 ---------------------------

doc/src/devdocs/gc.md

@@ -67,12 +67,6 @@ This scheme eliminates the need of explicitly keeping a flag to indicate a full
 ## Heuristics
 
 GC heuristics tune the GC by changing the size of the allocation interval between garbage collections.
-
-The GC heuristics measure how big the heap size is after a collection and set the next
-collection according to the algorithm described by https://dl.acm.org/doi/10.1145/3563323,
-in summary, it argues that the heap target should have a square root relationship with the live heap, and that it should also be scaled by how fast the GC is freeing objects and how fast the mutators are allocating.
-The heuristics measure the heap size by counting the number of pages that are in use and the objects that use malloc. Previously we measured the heap size by counting
-the alive objects, but that doesn't take into account fragmentation which could lead to bad decisions, that also meant that we used thread local information (allocations) to make
-decisions about a process wide (when to GC), measuring pages means the decision is global.
-
-The GC will do full collections when the heap size reaches 80% of the maximum allowed size.
+If a GC was unproductive, then we increase the size of the allocation interval to allow objects more time to die.
+If a GC returns a lot of space we can shrink the interval. The goal is to find a steady state where we are
+allocating just about the same amount as we are collecting.

src/gc-debug.c

@@ -1,10 +1,7 @@
 // This file is a part of Julia. License is MIT: https://julialang.org/license
 
 #include "gc.h"
-#include "julia.h"
 #include <inttypes.h>
-#include <stddef.h>
-#include <stdint.h>
 #include <stdio.h>
 
 // re-include assert.h without NDEBUG,
@@ -1220,25 +1217,15 @@ JL_DLLEXPORT void jl_enable_gc_logging(int enable) {
     gc_logging_enabled = enable;
 }
 
-void _report_gc_finished(uint64_t pause, uint64_t freed, int full, int recollect, int64_t live_bytes) JL_NOTSAFEPOINT {
+void _report_gc_finished(uint64_t pause, uint64_t freed, int full, int recollect) JL_NOTSAFEPOINT {
     if (!gc_logging_enabled) {
         return;
     }
-    jl_safe_printf("\nGC: pause %.2fms. collected %fMB. %s %s\n",
-        pause/1e6, freed/(double)(1<<20),
+    jl_safe_printf("GC: pause %.2fms. collected %fMB. %s %s\n",
+        pause/1e6, freed/1e6,
         full ? "full" : "incr",
         recollect ? "recollect" : ""
     );
-
-    jl_safe_printf("Heap stats: bytes_mapped %.2f MB, bytes_resident %.2f MB,\nheap_size %.2f MB, heap_target %.2f MB, Fragmentation %.3f\n",
-        jl_atomic_load_relaxed(&gc_heap_stats.bytes_mapped)/(double)(1<<20),
-        jl_atomic_load_relaxed(&gc_heap_stats.bytes_resident)/(double)(1<<20),
-        // live_bytes/(double)(1<<20), live byes tracking is not accurate.
-        jl_atomic_load_relaxed(&gc_heap_stats.heap_size)/(double)(1<<20),
-        jl_atomic_load_relaxed(&gc_heap_stats.heap_target)/(double)(1<<20),
-        (double)live_bytes/(double)jl_atomic_load_relaxed(&gc_heap_stats.heap_size)
-    );
-    // Should fragmentation use bytes_resident instead of heap_size?
 }
 
 #ifdef __cplusplus

src/gc-pages.c

@@ -52,8 +52,6 @@ char *jl_gc_try_alloc_pages_(int pg_cnt) JL_NOTSAFEPOINT
         // round data pointer up to the nearest gc_page_data-aligned
         // boundary if mmap didn't already do so.
         mem = (char*)gc_page_data(mem + GC_PAGE_SZ - 1);
-    jl_atomic_fetch_add_relaxed(&gc_heap_stats.bytes_mapped, pages_sz);
-    jl_atomic_fetch_add_relaxed(&gc_heap_stats.bytes_resident, pages_sz);
     return mem;
 }
 
@@ -117,7 +115,6 @@ NOINLINE jl_gc_pagemeta_t *jl_gc_alloc_page(void) JL_NOTSAFEPOINT
     // try to get page from `pool_freed`
     meta = pop_lf_back(&global_page_pool_freed);
     if (meta != NULL) {
-        jl_atomic_fetch_add_relaxed(&gc_heap_stats.bytes_resident, GC_PAGE_SZ);
         gc_alloc_map_set(meta->data, GC_PAGE_ALLOCATED);
         goto exit;
     }
@@ -191,7 +188,6 @@ void jl_gc_free_page(jl_gc_pagemeta_t *pg) JL_NOTSAFEPOINT
     madvise(p, decommit_size, MADV_DONTNEED);
 #endif
     msan_unpoison(p, decommit_size);
-    jl_atomic_fetch_add_relaxed(&gc_heap_stats.bytes_resident, -decommit_size);
 }
 
 #ifdef __cplusplus