From 59a892682908789fe74124f7b97ab11c9c8d2b92 Mon Sep 17 00:00:00 2001 From: Alexey Borzenkov Date: Sun, 27 Mar 2011 17:15:48 -0400 Subject: [PATCH] runtime: fix darwin/amd64 thread VM footprint On darwin amd64 it was impossible to create more that ~132 threads. While investigating I noticed that go consumes almost 1TB of virtual memory per OS thread and the reason for such a small limit of OS thread was because process was running out of virtual memory. While looking at bsdthread_create I noticed that on amd64 it wasn't using PTHREAD_START_CUSTOM. If you look at http://fxr.watson.org/fxr/source/bsd/kern/pthread_synch.c?v=xnu-1228 you will see that in that case darwin will use stack pointer as stack size, allocating huge amounts of memory for stack. This change fixes the issue and allows for creation of up to 2560 OS threads (which appears to be some Mac OS X limit) with relatively small virtual memory consumption. R=rsc CC=golang-dev https://golang.org/cl/4289075 --- src/pkg/runtime/darwin/amd64/sys.s | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/pkg/runtime/darwin/amd64/sys.s b/src/pkg/runtime/darwin/amd64/sys.s index 10d8f96df5..39398e065d 100644 --- a/src/pkg/runtime/darwin/amd64/sys.s +++ b/src/pkg/runtime/darwin/amd64/sys.s @@ -146,8 +146,7 @@ TEXT runtime·bsdthread_create(SB),7,$0 MOVQ mm+16(SP), SI // "arg" MOVQ stk+8(SP), DX // stack MOVQ gg+24(SP), R10 // "pthread" -// TODO(rsc): why do we get away with 0 flags here but not on 386? - MOVQ $0, R8 // flags + MOVQ $0x01000000, R8 // flags = PTHREAD_START_CUSTOM MOVQ $0, R9 // paranoia MOVQ $(0x2000000+360), AX // bsdthread_create SYSCALL