just to ensure 32-bit variables. Doing so broke and/or pessimized
i386's with 64-bit longs (unnecessary use of 64-bit variables
caused remarkably few problems in C code, but the inline asm here
tended to fail because there are no 64-bit registers). Since the
interfaces here are very machine-dependent and shouldn't be used
outside of the kernel, use a standard types of "known" width instead
of fixed-width types.
Changed all quad_t's to u_int64_t's. quad_t isn't standard, and
using signed types for 64-bit registers was bogus (but made no
difference).
to ensure 32-bit variables. Doing so broke i386's with 64-bit
longs. Use fixed-size integral types instead of plain ints, shorts,
chars and pointers since the bootinfo struct layout is a binary
interface. The boot blocks could reasonably be implemented using
16-bit code.
least unsuitable for holding an object pointer. This should have been
used to fix warnings about casts between pointers and ints on alphas.
Moved corresponding existing general typedef (fptrint_t) for function
pointers from the i386 <machine/profile.h> to a kernel-only typedef
in <machine/types.h>. Kludged libc/gmon/mcount.c so that it can
still see this typedef.
(long)(u_long)(u_int)-4 = 0x00000000fffffffc on machines with 32-bit
ints and 64-bit longs.
Restored %z format for printing signed hex. %+x shouldn't have been
used since it is an error in userland.
Prepared to nuke %n format by cloning it to %r. %n shouldn't have
been used because it means something completely different in
userland. Now %+r is equivalent to ddb's original %r, and %r is
equivalent to ddb's original %n.
Ignore '+' flag in combination with unsigned formats %{o,p,u,x}.
you can specify the corefile name by using:
sysctl -w kern.corefile="format"
where format is a pathname (relative or absolute -- default is "%N.core"),
with "%N" (process name), "%P" (process ID), and "%U" (user ID) formats.
Reviewed by: Mike Smith, with strong requests by Julian :)
(nonstandard %n and '+' with %x), and ones not found by -Wformat on
386's (some db_expr_t's are still printed as ints).
I decided not to change the arg type for %n from [unsigned] int to
register_t, since about half of the uses of %n are to print plain
ints and casting to [unsigned] long for %n is no harder than for %x.
`#if defined(ONE_THING)' is a style bug, and i386 instead of __i386__
is a bug, since i386 is never defined when the kernel is compiled
by with the default flags (`gcc -ansi ...'). Here the bug disabled
the call to pmap_setvidram(), so ISA video memory was not mapped
WC on 686's. The bug may have been masked by bugs in the committer's
version of gcc - `gcc -ansi' incorrectly defines i386 for gcc = the
version of egcs on the 2.2.6 cdrom.
bits. We used a private, wrong, version of `struct dirent' to help
break getdirentries(), and we use a silly check that the size of this
struct is a power of 2 to help break mount() if getdirentries() would
not work. This fix just changes the struct to match `struct dirent'
(except for the name length).
not actually work for cross compiling, but that is another problem.)
Honor LDFLAGS for building internal tools. (Tools should normally
be built static to avoid problems with picking up target shared
libraries. bsd.kmod doesn't set -static yet, and has some problems
with `LDFLAGS=-static ...' in the environment.)
writes of size (100,208]+N*MCLBYTES.
The bug:
sosend() hands each mbuf off to the protocol output routine as soon as it
has copied it, in the hopes of increasing parallelism (see
http://www.kohala.com/~rstevens/vanj.88jul20.txt ). This works well for
TCP as long as the first mbuf handed off is at least the MSS. However,
when doing small writes (between MHLEN and MINCLSIZE), the transaction is
split into 2 small MBUF's and each is individually handed off to TCP.
TCP assumes that the first small mbuf is the whole transaction, so sends
a small packet. When the second small mbuf arrives, Nagle prevents TCP
from sending it so it must wait for a (potentially delayed) ACK. This
sends throughput down the toilet.
The workaround:
Set the "atomic" flag when we're doing small writes. The "atomic" flag
has two meanings:
1. Copy all of the data into a chain of mbufs before handing off to the
protocol.
2. Leave room for a datagram header in said mbuf chain.
TCP wants the first but doesn't want the second. However, the second
simply results in some memory wastage (but is why the workaround is a
hack and not a fix).
The real fix:
The real fix for this problem is to introduce something like a "requested
transfer size" variable in the socket->protocol interface. sosend()
would then accumulate an mbuf chain until it exceeded the "requested
transfer size". TCP could set it to the TCP MSS (note that the
current interface causes strange TCP behaviors when the MSS > MCLBYTES;
nobody notices because MCLBYTES > ethernet's MTU).
