* [RFC] use MSG_NOSIGNAL under Linux 2.2+
@ 2015-02-13 20:12 Eric Wong
2015-02-13 20:33 ` Eric Wong
0 siblings, 1 reply; 2+ messages in thread
From: Eric Wong @ 2015-02-13 20:12 UTC (permalink / raw)
To: kgio-public
I don't consider this a serious patch because it only affects
rare error handling paths and is not going to make a difference
in real-world use. But oh well, I'm low on caffeine right now :x
MSG_NOSIGNAL exists on any machine that supports MSG_DONTWAIT.
While Ruby itself ignore SIGPIPE, this can save a few cycles
inside the kernel by avoiding the no-op signal delivery
in the first place.
---
ext/kgio/read.c | 10 ++++++++--
ext/kgio/write.c | 2 +-
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/ext/kgio/read.c b/ext/kgio/read.c
index 472a592..76b1638 100644
--- a/ext/kgio/read.c
+++ b/ext/kgio/read.c
@@ -5,8 +5,14 @@
#include "nonblock.h"
static VALUE sym_wait_readable;
+/*
+ * MSG_NOSIGNAL exists on any machine that supports MSG_DONTWAIT.
+ * While Ruby itself ignore SIGPIPE, this can save a few cycles
+ * inside the kernel by avoiding the no-op signal delivery
+ * in the first place.
+ */
#ifdef USE_MSG_DONTWAIT
-static const int peek_flags = MSG_DONTWAIT|MSG_PEEK;
+static const int peek_flags = MSG_DONTWAIT|MSG_PEEK|MSG_NOSIGNAL;
/* we don't need these variants, we call kgio_autopush_recv directly */
static inline void kgio_autopush_read(VALUE io) { }
@@ -162,7 +168,7 @@ static VALUE my_recv(int io_wait, int argc, VALUE *argv, VALUE io)
if (a.len > 0) {
retry:
- n = (long)recv(a.fd, a.ptr, a.len, MSG_DONTWAIT);
+ n = (long)recv(a.fd, a.ptr, a.len, MSG_DONTWAIT|MSG_NOSIGNAL);
if (read_check(&a, n, "recv", io_wait) != 0)
goto retry;
}
diff --git a/ext/kgio/write.c b/ext/kgio/write.c
index ce4aa75..c97b049 100644
--- a/ext/kgio/write.c
+++ b/ext/kgio/write.c
@@ -123,7 +123,7 @@ static VALUE my_send(VALUE io, VALUE str, int io_wait)
prepare_write(&a, io, str);
retry:
- n = (long)send(a.fd, a.ptr, a.len, MSG_DONTWAIT);
+ n = (long)send(a.fd, a.ptr, a.len, MSG_DONTWAIT|MSG_NOSIGNAL);
if (write_check(&a, n, "send", io_wait) != 0)
goto retry;
if (TYPE(a.buf) != T_SYMBOL)
--
EW
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC] use MSG_NOSIGNAL under Linux 2.2+
2015-02-13 20:12 [RFC] use MSG_NOSIGNAL under Linux 2.2+ Eric Wong
@ 2015-02-13 20:33 ` Eric Wong
0 siblings, 0 replies; 2+ messages in thread
From: Eric Wong @ 2015-02-13 20:33 UTC (permalink / raw)
To: kgio-public
Eric Wong <e@80x24.org> wrote:
> ext/kgio/read.c | 10 ++++++++--
> ext/kgio/write.c | 2 +-
And further inspection of the Linux kernel reveals MSG_NOSIGNAL only
affects writers, not readers, so the read.c changes are no-ops.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-02-13 20:12 [RFC] use MSG_NOSIGNAL under Linux 2.2+ Eric Wong
2015-02-13 20:33 ` Eric Wong
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