44 lines
1.5 KiB
Diff
44 lines
1.5 KiB
Diff
From 48fed5c55b5183e6d44702dfdccd3b5325d8689c Mon Sep 17 00:00:00 2001
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From: David Herrmann <dh.herrmann@gmail.com>
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Date: Fri, 3 Oct 2014 15:54:21 +0200
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Subject: [PATCH] pty: optimize read loop
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As it turns out, I can actually send data to the pty faster than the
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terminal can read. Therefore, make sure we read as much data as possible
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but bail out early enough to not cause starvation.
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Kernel TTY buffers are 4k, so reduce the overall buffer size, but read
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more than once if possible (up to 8 times sounds reasonable).
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---
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src/shared/pty.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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diff --git a/src/shared/pty.c b/src/shared/pty.c
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index adcb32d0be..52a426c0e1 100644
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--- a/src/shared/pty.c
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+++ b/src/shared/pty.c
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@@ -67,7 +67,7 @@
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#include "ring.h"
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#include "util.h"
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-#define PTY_BUFSIZE 16384
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+#define PTY_BUFSIZE 4096
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enum {
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PTY_ROLE_UNKNOWN,
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@@ -305,11 +305,11 @@ static int pty_dispatch_read(Pty *pty) {
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/*
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* We're edge-triggered, means we need to read the whole queue. This,
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* however, might cause us to stall if the writer is faster than we
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- * are. Therefore, we read twice and if the second read still returned
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- * data, we reschedule.
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+ * are. Therefore, try reading as much as 8 times (32KiB) and only
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+ * bail out then.
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*/
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- for (i = 0; i < 2; ++i) {
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+ for (i = 0; i < 8; ++i) {
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len = read(pty->fd, pty->in_buf, sizeof(pty->in_buf) - 1);
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if (len < 0) {
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if (errno == EINTR)
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