[RFC][PATCH v3 2/4] printk: do not console_cont_flush() on every jump to again

From	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Newsgroups	linux.kernel
Subject	[RFC][PATCH v3 2/4] printk: do not console_cont_flush() on every jump to again
Date	2016-01-23 09:20 +0100
Message-ID	<qU1Al-8nr-1@gated-at.bofh.it> (permalink)
References	<qU1Al-8nr-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Every jump to `again' label will call console_cont_flush(),
which is not really something big -- it just adds one extra
raw_spin_lock_irqsave/raw_spin_unlock_irqrestore. However, to
keep the previous behaviour we can call console_cont_flush()
only when `retry' is false -- which happens once, all jumps
to `again' label have `retry' set to true.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 kernel/printk/printk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c39232a..dc722fc 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2213,7 +2213,7 @@ void console_unlock(void)
 	static u64 seen_seq;
 	unsigned long flags;
 	bool wake_klogd = false;
-	bool do_cond_resched, retry;
+	bool do_cond_resched, retry = false;
 
 	if (console_suspended) {
 		up_console_sem();
@@ -2246,7 +2246,8 @@ again:
 	}
 
 	/* flush buffered message fragment immediately to console */
-	console_cont_flush(text, sizeof(text));
+	if (!retry)
+		console_cont_flush(text, sizeof(text));
 
 	for (;;) {
 		struct printk_log *msg;
-- 
2.7.0

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[RFC][PATCH v3 2/4] printk: do not console_cont_flush() on every jump to again Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-01-23 09:20 +0100

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