From 89f185fe8a036b0fabce30b20c480cf1c832bdd7 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Thu, 26 Jun 2014 11:54:39 -0400 Subject: all: remove 'extern register M *m' from runtime MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The runtime has historically held two dedicated values g (current goroutine) and m (current thread) in 'extern register' slots (TLS on x86, real registers backed by TLS on ARM). This CL removes the extern register m; code now uses g->m. On ARM, this frees up the register that formerly held m (R9). This is important for NaCl, because NaCl ARM code cannot use R9 at all. The Go 1 macrobenchmarks (those with per-op times >= 10 µs) are unaffected: BenchmarkBinaryTree17 5491374955 5471024381 -0.37% BenchmarkFannkuch11 4357101311 4275174828 -1.88% BenchmarkGobDecode 11029957 11364184 +3.03% BenchmarkGobEncode 6852205 6784822 -0.98% BenchmarkGzip 650795967 650152275 -0.10% BenchmarkGunzip 140962363 141041670 +0.06% BenchmarkHTTPClientServer 71581 73081 +2.10% BenchmarkJSONEncode 31928079 31913356 -0.05% BenchmarkJSONDecode 117470065 113689916 -3.22% BenchmarkMandelbrot200 6008923 5998712 -0.17% BenchmarkGoParse 6310917 6327487 +0.26% BenchmarkRegexpMatchMedium_1K 114568 114763 +0.17% BenchmarkRegexpMatchHard_1K 168977 169244 +0.16% BenchmarkRevcomp 935294971 914060918 -2.27% BenchmarkTemplate 145917123 148186096 +1.55% Minux previous reported larger variations, but these were caused by run-to-run noise, not repeatable slowdowns. Actual code changes by Minux. I only did the docs and the benchmarking. LGTM=dvyukov, iant, minux R=minux, josharian, iant, dave, bradfitz, dvyukov CC=golang-codereviews https://golang.org/cl/109050043 --- src/pkg/runtime/os_linux.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'src/pkg/runtime/os_linux.c') diff --git a/src/pkg/runtime/os_linux.c b/src/pkg/runtime/os_linux.c index 8a945242b9..31cbdb0ad5 100644 --- a/src/pkg/runtime/os_linux.c +++ b/src/pkg/runtime/os_linux.c @@ -196,6 +196,7 @@ void runtime·mpreinit(M *mp) { mp->gsignal = runtime·malg(32*1024); // OS X wants >=8K, Linux >=2K + mp->gsignal->m = mp; } // Called to initialize a new m (including the bootstrap m). @@ -204,7 +205,7 @@ void runtime·minit(void) { // Initialize signal handling. - runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024); + runtime·signalstack((byte*)g->m->gsignal->stackguard - StackGuard, 32*1024); runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset)); } -- cgit v1.3-5-g9baa