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From: Ed Schouten <ed@FreeBSD.org>
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Subject: PERFORCE change 148083 for review
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http://perforce.freebsd.org/chv.cgi?CH=148083

Change 148083 by ed@ed_dull on 2008/08/22 05:31:39

	Properly document the SNP_*_BUFSIZE definitions.
	
	Requested by:	sam

Affected files ...

.. //depot/projects/mpsafetty/sys/dev/snp/snp.c#11 edit

Differences ...

==== //depot/projects/mpsafetty/sys/dev/snp/snp.c#11 (text+ko) ====

@@ -48,8 +48,19 @@
     "tty snoop registration");
 static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device");
 
-#define SNP_INPUT_BUFSIZE	16	/* For uiomove(). */
-#define SNP_OUTPUT_BUFSIZE	16384	/* For the ttyoutq. */
+/*
+ * There is no need to have a big input buffer. In most typical setups,
+ * we won't inject much data into the TTY, because users can't type
+ * really fast.
+ */
+#define SNP_INPUT_BUFSIZE	16
+/*
+ * The output buffer has to be really big. Right now we don't support
+ * any form of flow control, which means we lost any data we can't
+ * accept. We set the output buffer size to about twice the size of a
+ * pseudo-terminal/virtual console's output buffer.
+ */
+#define SNP_OUTPUT_BUFSIZE	16384
 
 static d_open_t		snp_open;
 static d_read_t		snp_read;