From 3a4d5c94e959359ece6d6b55045c3f046677f55c Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 14 Jan 2010 06:17:27 +0000 Subject: vhost_net: a kernel-level virtio server What it is: vhost net is a character device that can be used to reduce the number of system calls involved in virtio networking. Existing virtio net code is used in the guest without modification. There's similarity with vringfd, with some differences and reduced scope - uses eventfd for signalling - structures can be moved around in memory at any time (good for migration, bug work-arounds in userspace) - write logging is supported (good for migration) - support memory table and not just an offset (needed for kvm) common virtio related code has been put in a separate file vhost.c and can be made into a separate module if/when more backends appear. I used Rusty's lguest.c as the source for developing this part : this supplied me with witty comments I wouldn't be able to write myself. What it is not: vhost net is not a bus, and not a generic new system call. No assumptions are made on how guest performs hypercalls. Userspace hypervisors are supported as well as kvm. How it works: Basically, we connect virtio frontend (configured by userspace) to a backend. The backend could be a network device, or a tap device. Backend is also configured by userspace, including vlan/mac etc. Status: This works for me, and I haven't see any crashes. Compared to userspace, people reported improved latency (as I save up to 4 system calls per packet), as well as better bandwidth and CPU utilization. Features that I plan to look at in the future: - mergeable buffers - zero copy - scalability tuning: figure out the best threading model to use Note on RCU usage (this is also documented in vhost.h, near private_pointer which is the value protected by this variant of RCU): what is happening is that the rcu_dereference() is being used in a workqueue item. The role of rcu_read_lock() is taken on by the start of execution of the workqueue item, of rcu_read_unlock() by the end of execution of the workqueue item, and of synchronize_rcu() by flush_workqueue()/flush_work(). In the future we might need to apply some gcc attribute or sparse annotation to the function passed to INIT_WORK(). Paul's ack below is for this RCU usage. (Includes fixes by Alan Cox , David L Stevens , Chris Wright ) Acked-by: Rusty Russell Acked-by: Arnd Bergmann Acked-by: "Paul E. McKenney" Signed-off-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- include/linux/Kbuild | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/Kbuild') diff --git a/include/linux/Kbuild b/include/linux/Kbuild index 756f831cbdd5..d93080748a91 100644 --- a/include/linux/Kbuild +++ b/include/linux/Kbuild @@ -362,6 +362,7 @@ unifdef-y += uio.h unifdef-y += unistd.h unifdef-y += usbdevice_fs.h unifdef-y += utsname.h +unifdef-y += vhost.h unifdef-y += videodev2.h unifdef-y += videodev.h unifdef-y += virtio_config.h -- cgit v1.2.3 From d02f0cff1da4a1bd609e8d3eae3a2e85459cd8a1 Mon Sep 17 00:00:00 2001 From: dann frazier Date: Tue, 23 Feb 2010 08:38:42 +0100 Subject: cciss: export linux/cciss_defs.h header 'make headers_check' began to fail after cciss_defs.h was introduced in: 429c42c9d246f5bda868495c09974312a0177328 usr/include/linux/cciss_ioctl.h:6: included file 'linux/cciss_defs.h' is not exported Fix this by exporting cciss_defs.h Signed-off-by: dann frazier Signed-off-by: Jens Axboe --- include/linux/Kbuild | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/Kbuild') diff --git a/include/linux/Kbuild b/include/linux/Kbuild index 756f831cbdd5..91be0d896322 100644 --- a/include/linux/Kbuild +++ b/include/linux/Kbuild @@ -43,6 +43,7 @@ header-y += blkpg.h header-y += bpqether.h header-y += bsg.h header-y += can.h +header-y += cciss_defs.h header-y += cdk.h header-y += chio.h header-y += coda_psdev.h -- cgit v1.2.3 From d2e82add832f9c95376d004d565c5e164c99b9ec Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Tue, 23 Feb 2010 23:36:25 +0100 Subject: OMAP: DSS2: OMAPFB: install omapfb.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit omapfb has several custom ioctls so user space needs the header in order to utilize them. Signed-off-by: Ville Syrjälä Signed-off-by: Tomi Valkeinen --- include/linux/Kbuild | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/Kbuild') diff --git a/include/linux/Kbuild b/include/linux/Kbuild index 756f831cbdd5..aa80d7a2dee7 100644 --- a/include/linux/Kbuild +++ b/include/linux/Kbuild @@ -125,6 +125,7 @@ header-y += nfs2.h header-y += nfs4_mount.h header-y += nfs_mount.h header-y += nl80211.h +header-y += omapfb.h header-y += param.h header-y += pci_regs.h header-y += perf_event.h -- cgit v1.2.3