On Fri, 2024-03-08 at 11:54 -0500, Jeff Layton wrote:
> On Thu, 2024-03-07 at 16:39 -0500, trondmy@xxxxxxxxx wrote:
> > From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> >
> > When creating a listener socket to be handed to
> > /proc/fs/nfsd/portlist,
> > we currently limit the number of backlogged connections to 64.
> > Since
> > that value was chosen in 2006, the scale at which data centres
> > operate
> > has changed significantly. Given a modern server with many
> > thousands of
> > clients, a limit of 64 connections can create bottlenecks,
> > particularly
> > at at boot time.
> > By converting to using an argument of -1, we allow the backlog to
> > be set
> > by the default value in /proc/sys/net/core/somaxconn.
> >
> > Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > ---
> > utils/nfsd/nfssvc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/utils/nfsd/nfssvc.c b/utils/nfsd/nfssvc.c
> > index 46452d972407..c781054dbdae 100644
> > --- a/utils/nfsd/nfssvc.c
> > +++ b/utils/nfsd/nfssvc.c
> > @@ -205,7 +205,7 @@ nfssvc_setfds(const struct addrinfo *hints,
> > const char *node, const char *port)
> > rc = errno;
> > goto error;
> > }
> > - if (addr->ai_protocol == IPPROTO_TCP &&
> > listen(sockfd, 64)) {
> > + if (addr->ai_protocol == IPPROTO_TCP &&
> > listen(sockfd, -1)) {
> > xlog(L_ERROR, "unable to create listening
> > socket: "
> > "errno %d (%m)", errno);
> > rc = errno;
>
> It does look like the kernel casts the value to unsigned int before
> trying to interpret it, but that doesn't seem to be documented
> anywhere
> that I can find. It's certainly not in the manpage
>
> There is this in /usr/include/bits/socket.h:
>
> /* Maximum queue length specifiable by listen. */
> #define SOMAXCONN 4096
>
> ...but I guess that's problematic if you set "somaxconn" sysctl
> higher.
> I wonder if SOMAXCONN should be redefined as "(int)UINT_MAX" in the
> UAPI
> headers?
Fair enough. I'll respin with SOMAXCONN. It looks as if that is what
POSIX expects us to use as well.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
