From 3ab98a471c4b1aec557583e674beacd15be4955d Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Fri, 15 Feb 2013 18:55:09 +0000 Subject: runtime: Do not reserve huge amount of swap on 32 bit architectures. The mmap() call which reserves the arena should have MAP_NORESERVE flag as in typical cases this memory will never be (fully) needed. This matters in environments which do not do Linux style memory overcommit, such as OpenIndiana/OpenSolaris/Solaris. The MAP_NORESERVE flag does not exist on all operating systems (for example FreeBSD). Therefore we define it to zero value in case it does not exist. Fixes issue 21. From-SVN: r196088 --- libgo/runtime/mem.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'libgo') diff --git a/libgo/runtime/mem.c b/libgo/runtime/mem.c index e70694c..e606bdd 100644 --- a/libgo/runtime/mem.c +++ b/libgo/runtime/mem.c @@ -18,6 +18,10 @@ #endif #endif +#ifndef MAP_NORESERVE +#define MAP_NORESERVE 0 +#endif + #ifdef USE_DEV_ZERO static int dev_zero = -1; #endif @@ -134,7 +138,11 @@ runtime_SysReserve(void *v, uintptr n) return v; } - p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0); + // Use the MAP_NORESERVE mmap() flag here because typically most of + // this reservation will never be used. It does not make sense + // reserve a huge amount of unneeded swap space. This is important on + // systems which do not overcommit memory by default. + p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_NORESERVE, fd, 0); if(p == MAP_FAILED) return nil; return p; -- cgit v1.1