Remove support for lazy deallocation. Benchmarks across a wide range of

allocation patterns, number of CPUs, and MALLOC_OPTIONS settings indicate
that lazy deallocation has the potential to worsen throughput dramatically.
Performance degradation occurs when multiple threads try to clear the lazy
free cache simultaneously.  Various experiments to avoid this bottleneck
failed to completely solve this problem, while adding yet more complexity.

1 files changed, 1 insertions, 12 deletions

diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3
index 1d33e6a..7cd04de 100644
--- a/lib/libc/stdlib/malloc.3
+++ b/lib/libc/stdlib/malloc.3
@@ -32,7 +32,7 @@
 .\"     @(#)malloc.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd February 5, 2008
+.Dd February 17, 2008
 .Dt MALLOC 3
 .Os
 .Sh NAME
@@ -231,17 +231,6 @@ This is intended for debugging and will impact performance negatively.
 .It K
 Double/halve the virtual memory chunk size.
 The default chunk size is 1 MB.
-.It L
-Double/halve the per-arena number of slots for lazy deallocation.
-Lazy deallocation can decrease lock contention, especially for programs that use
-the producer/consumer model.
-The default is 256 slots per arena (so
-.Ev MALLOC_OPTIONS=9l
-will disable lazy deallocation), but note that due to algorithmic details, the
-cache is typically flushed well before it completely fills.
-This option has no impact unless there are multiple CPUs, and lazy deallocation
-does not activate unless the program uses multiple threads.
-This option is not available for some configurations (non-PIC).
 .It M
 Use
 .Xr mmap 2