1e4ad9ce28
the high kernel calls into a protocol stack to perform requests on the user's behalf. We replace the pr_usrreq() entry in struct protosw with a pointer to a structure containing pointers to functions which implement the various reuqests; each function is declared with the correct type and number of arguments. (This is unlike the current scheme in which a quarter of the requests take arguments of type other than (struct mbuf *) and the difference is papered over with casts.) There are a few benefits to this new scheme: 1) Arguments are passed with their correct types, and null-pointer dummies are no longer necessary. 2) There should be slightly better caching effects from eliminating the prximity to extraneous code and th switch in pr_usrreq(). 3) It becomes much easier to change the types of the arguments to something other than `struct mbuf *' (e.g.,pushing the work of sosend() into the protocol as advocated by Van Jacobson). There is one principal drawback: existing protocol stacks need to be modified. This is alleviated by compatibility code in uipc_socket2.c and uipc_domain.c which emulates the new interface in terms of the old and vice versa. This idea is not original to me. I read about what Jacobson did in one of his papers and have tried to implement the first steps towards something like that here. Much work remains to be done. |
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alpha | ||
amd64 | ||
compat/linux | ||
compile | ||
conf | ||
ddb | ||
dev | ||
fs | ||
geom | ||
gnu | ||
i386 | ||
isa | ||
isofs/cd9660 | ||
kern | ||
libkern | ||
miscfs | ||
modules | ||
msdosfs | ||
net | ||
netatalk | ||
netinet | ||
netipx | ||
netkey | ||
netns | ||
nfs | ||
nfsclient | ||
nfsserver | ||
pc98 | ||
pccard | ||
pci | ||
powerpc/include | ||
rpc | ||
scsi | ||
sys | ||
tools | ||
ufs | ||
vm | ||
Makefile |