From de694c984027407b78ba1548404f7e4da7d45d93 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Wed, 8 Feb 2017 07:58:07 +0100 Subject: [PATCH] pipe.7: Clarify that default pipe capacity is 16 pages The statement that the default pipe capacity is 65536 bytes is accurate only on systems where the page size is 4096B. See the use of PIPE_DEF_BUFFERS in the kernel source. Signed-off-by: Michael Kerrisk --- man7/pipe.7 | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/man7/pipe.7 b/man7/pipe.7 index 3df4e0866..cff9b75e9 100644 --- a/man7/pipe.7 +++ b/man7/pipe.7 @@ -132,8 +132,9 @@ so that a writing process does not remain blocked. In Linux versions before 2.6.11, the capacity of a pipe was the same as the system page size (e.g., 4096 bytes on i386). -Since Linux 2.6.11, the pipe capacity is 65536 bytes. -Since Linux 2.6.35, the default pipe capacity is 65536 bytes, +Since Linux 2.6.11, the pipe capacity is 16 pages +(i.e., 65,536 bytes in a system with a page size of 4096 bytes). +Since Linux 2.6.35, the default pipe capacity is 16 pages, but the capacity can be queried and set using the .BR fcntl (2) .BR F_GETPIPE_SZ