From b026eddfeac766240ce0a06e3ec8a741d57c8bb8 Mon Sep 17 00:00:00 2001 From: Alan Somers Date: Fri, 13 Dec 2013 21:49:41 +0000 Subject: [PATCH] sbin/devd/devd.cc Increase the size of devd's client socket's send buffer from the default (8k) to 128k. This prevents clients from getting POLLHUPped during event storms. For example, during zpool creation, the kernel emits a resource.fs.zfs.statechange event for every vdev in the pool. A 128k buffer is large enough to hold the statechange events for a pool with nearly 800 drives. Reviewed by: ian, imp Approved by: ken (mentor) Sponsored by: Spectra Logic Corp MFC after: 4 weeks --- sbin/devd/devd.cc | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/sbin/devd/devd.cc b/sbin/devd/devd.cc index 21816e59c58..b64c459a579 100644 --- a/sbin/devd/devd.cc +++ b/sbin/devd/devd.cc @@ -104,6 +104,19 @@ __FBSDID("$FreeBSD$"); #define CF "/etc/devd.conf" #define SYSCTL "hw.bus.devctl_disable" +/* + * Since the client socket is nonblocking, we must increase its send buffer to + * handle brief event storms. On FreeBSD, AF_UNIX sockets don't have a receive + * buffer, so the client can't increate the buffersize by itself. + * + * For example, when creating a ZFS pool, devd emits one 165 character + * resource.fs.zfs.statechange message for each vdev in the pool. A 64k + * buffer has enough space for almost 400 drives, which would be very large but + * not impossibly large pool. A 128k buffer has enough space for 794 drives, + * which is more than can fit in a rack with modern technology. + */ +#define CLIENT_BUFSIZE 131072 + using namespace std; extern FILE *yyin; @@ -892,6 +905,7 @@ void new_client(int fd) { int s; + int sndbuf_size; /* * First go reap any zombie clients, then accept the connection, and @@ -901,10 +915,15 @@ new_client(int fd) check_clients(); s = accept(fd, NULL, NULL); if (s != -1) { + sndbuf_size = CLIENT_BUFSIZE; + if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, &sndbuf_size, + sizeof(sndbuf_size))) + err(1, "setsockopt"); shutdown(s, SHUT_RD); clients.push_back(s); ++num_clients; - } + } else + err(1, "accept"); } static void