svn commit: r201743 - head/lib/libc/sys
Konstantin Belousov
kib at FreeBSD.org
Thu Jan 7 13:31:01 UTC 2010
Author: kib
Date: Thu Jan 7 13:31:00 2010
New Revision: 201743
URL: http://svn.freebsd.org/changeset/base/201743
Log:
Give some information on SF_MNOWAIT flag.
MFC after: 3 days
Modified:
head/lib/libc/sys/sendfile.2
Modified: head/lib/libc/sys/sendfile.2
==============================================================================
--- head/lib/libc/sys/sendfile.2 Thu Jan 7 12:58:03 2010 (r201742)
+++ head/lib/libc/sys/sendfile.2 Thu Jan 7 13:31:00 2010 (r201743)
@@ -116,9 +116,17 @@ Busy servers may benefit by transferring
block to a separate I/O worker thread.
.It
.Dv SF_MNOWAIT .
-(description missing)
+Do not wait for some kernel resource to become available,
+in particular,
+.Vt mbuf
+and
+.Vt sf_buf .
+The flag does not make the
+.Fn sendfile
+syscall trully non-blocking, since other resources are still allocated
+in blocking fashion.
.It
-.Dv SF_SYNC ,
+.Dv SF_SYNC .
.Nm
sleeps until the network stack no longer references the VM pages
of the file, making subsequent modifications to it safe.
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