This merge changes the device switch tables from static array to
dynamically generated by config(8).
- All device switches is defined as a constant structure in device drivers.
- The new grammer ``device-major'' is introduced to ``files''.
device-major <prefix> char <num> [block <num>] [<rules>]
- All device major numbers must be listed up in port dependent majors.<arch>
by using this grammer.
- Added the new naming convention.
The name of the device switch must be <prefix>_[bc]devsw for auto-generation
of device switch tables.
- The backward compatibility of loading block/character device
switch by LKM framework is broken. This is necessary to convert
from block/character device major to device name in runtime and vice versa.
- The restriction to assign device major by LKM is completely removed.
We don't need to reserve LKM entries for dynamic loading of device switch.
- In compile time, device major numbers list is packed into the kernel and
the LKM framework will refer it to assign device major number dynamically.
Fix 2 bugs with MSG_WAITALL. The first is to not block forever if one is
trying to MSG_PEEK for more than the socket can hold. The second is that
before sleeping waiting for more data, upcall the protocol telling it you
have just received data so it can kick itself to re-fill the just drained
socket buffer.
* Keep pointers to the first and last mbufs of the last record in the
socket buffer.
* Use the sb_lastrecord pointer in the sbappend*() family of functions
to avoid traversing the packet chain to find the last record.
* Add a new sbappend_stream() function for stream protocols which
guarantee that there will never be more than one record in the
socket buffer. This function uses the sb_mbtail pointer to perform
the data insertion. Make TCP use sbappend_stream().
On a profiling run, this makes sbappend of a TCP transmission using
a 1M socket buffer go from 50% of the time to .02% of the time.
Thanks to Bill Sommerfeld and YAMAMOTO Takashi for their debugging
assistance!
the block comment at the top of the file:
This module provides kernel support for testing network
throughput from the perspective of the kernel. It is
similar in spirit to the classic ttcp network benchmark
program, the main difference being that with kttcp, the
kernel is the source and sink of the data.
Testing like this is useful for a few reasons:
1. This allows us to know what kind of performance we can
expect from network applications that run in the kernel
space, such as the NFS server or the NFS client. These
applications don't have to move the data to/from userspace,
and so benchmark programs which run in userspace don't
give us an accurate model.
2. Since data received is just thrown away, the receiver
is very fast. This can provide better exercise for the
sender at the other end.
3. Since the NetBSD kernel currently uses a run-to-completion
scheduling model, kttcp provides a benchmark model where
preemption of the benchmark program is not an issue.
There is a companion "kttcp" user program which uses the kttcp
pseudo-device.
Largely written by Frank van der Linden, with some modifications
from me.
gehenna