tor

commit c55e633f7446fea7b73be75f6713fad6493edf05
parent 033f8044292b74e6a46a719476b9633e5d79d978
Author: David Goulet <dgoulet@torproject.org>
Date:   Mon, 22 Jun 2020 15:28:47 -0400

kist: Document a magic value in channel_should_write_to_kernel()

Closes #40008

Signed-off-by: David Goulet <dgoulet@torproject.org>

Diffstat:
M
src/core/or/scheduler_kist.c
 | 
5
+++++

1 file changed, 5 insertions(+), 0 deletions(-)
diff --git a/src/core/or/scheduler_kist.c b/src/core/or/scheduler_kist.c
@@ -445,6 +445,11 @@ update_socket_written(socket_table_t *table, channel_t *chan, size_t bytes)
  * one cell for each and bouncing back and forth. This KIST impl avoids that
  * by only writing a channel's outbuf to the kernel if it has 8 cells or more
  * in it.
+ *
+ * Note: The number 8 has been picked for no particular reasons except that it
+ * is 4096 bytes which is a common number for buffering. A TLS record can hold
+ * up to 16KiB thus using 8 cells means that a relay will at most send a TLS
+ * record of 4KiB or 1/4 of the maximum capacity of a TLS record.
  */
 MOCK_IMPL(int, channel_should_write_to_kernel,
           (outbuf_table_t *table, channel_t *chan))