PERFORCE change 137397 for review
Robert Watson
rwatson at FreeBSD.org
Tue Mar 11 14:31:21 UTC 2008
http://perforce.freebsd.org/chv.cgi?CH=137397
Change 137397 by rwatson at rwatson_cinnamon on 2008/03/11 14:30:41
A bit more detail on the shared memory model and a pointer to
bpf(4).
Affected files ...
.. //depot/projects/zcopybpf/src/sys/net/bpf_zerocopy.c#29 edit
Differences ...
==== //depot/projects/zcopybpf/src/sys/net/bpf_zerocopy.c#29 (text+ko) ====
@@ -60,7 +60,11 @@
* are mapped into the kernel address space using sf_bufs and used directly
* by BPF. Memory is wired since page faults cannot be tolerated in the
* contexts where the buffers are copied to (locks held, interrupt context,
- * etc).
+ * etc). Access to shared memory buffers is synchronized using a header on
+ * each buffer, allowing the number of system calls to go to zero as BPF
+ * reaches saturation (buffers filled as fast as they can be drained by the
+ * user process). Full details of the protocol for communicating between the
+ * user process and BPF may be found in bpf(4).
*/
/*
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