27 Aug, 2010
1 commit
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These days the headers we use are in glibc. If those are too old, you can
add the -I lines to get the kernel headers.In file included from ../../include/linux/if_tun.h:19,
from lguest.c:33:
../../include/linux/types.h:13:2: warning: #warning "Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders"
lguest.c: In function ‘setup_tun_net’:
lguest.c:1456: warning: dereferencing pointer ‘sin’ does break strict-aliasing rules
lguest.c:1457: warning: dereferencing pointer ‘sin’ does break strict-aliasing rules
lguest.c:1450: note: initialized from hereSigned-off-by: Rusty Russell
23 Apr, 2010
1 commit
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Fix obvious cases of "it's" being used when "its" was meant.
Signed-off-by: Francis Galiegue
Acked-by: Randy Dunlap
Signed-off-by: Jiri Kosina
24 Feb, 2010
1 commit
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Two years ago 5bbf89fc2608 removed the horrible bzImage unpacking code.
Now it's time to remove the unneeded zlib.h include, too.Signed-off-by: Rusty Russell
04 Dec, 2009
1 commit
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That is "success", "unknown", "through", "performance", "[re|un]mapping"
, "access", "default", "reasonable", "[con]currently", "temperature"
, "channel", "[un]used", "application", "example","hierarchy", "therefore"
, "[over|under]flow", "contiguous", "threshold", "enough" and others.Signed-off-by: André Goddard Rosa
Signed-off-by: Jiri Kosina
22 Oct, 2009
1 commit
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Rusty,
commit 3ca4f5ca73057a617f9444a91022d7127041970a
virtio: add virtio IDs file
moved all device IDs into a single file. While the change itself is
a very good one, it can break userspace applications. For example
if a userspace tool wanted to get the ID of virtio_net it used to
include virtio_net.h. This does no longer work, since virtio_net.h
does not include virtio_ids.h.
This patch moves all "#include " from the C
files into the header files, making the header files compatible with
the old ones.In addition, this patch exports virtio_ids.h to userspace.
CC: Fernando Luis Vazquez Cao
Signed-off-by: Christian Borntraeger
Signed-off-by: Rusty Russell
23 Sep, 2009
2 commits
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VIRTIO_F_NOTIFY_ON_EMPTY indicates to the Guest that we will hit them with
an interrupt every time the xmit queue is emptied.Because it results in lots of tx interrupts, modern Guests probably don't
want it, so let's only force it when they accept the option.Signed-off-by: Rusty Russell
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Virtio IDs are spread all over the tree which makes assigning new IDs
bothersome. Putting them together should make the process less error-prone.Signed-off-by: Fernando Luis Vazquez Cao
Signed-off-by: Rusty Russell
30 Jul, 2009
4 commits
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I've been doing this for years, and akpm picked me up on it about 12
months ago. lguest partly serves as example code, so let's do it Right.Also, remove two unused fields in struct vblk_info in the example launcher.
Signed-off-by: Rusty Russell
Cc: Ingo Molnar -
Every so often, after code shuffles, I need to go through and unbitrot
the Lguest Journey (see drivers/lguest/README). Since we now use RCU in
a simple form in one place I took the opportunity to expand that explanation.Signed-off-by: Rusty Russell
Cc: Ingo Molnar
Cc: Paul McKenney -
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does. And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.Signed-off-by: Rusty Russell
Cc: Ingo Molnar -
1d589bb16b825b3a7b4edd34d997f1f1f953033d "Add serial number support
for virtio_blk, V4a" extended 'struct virtio_blk_config' to 536 bytes.
Lguest and S/390 both use an 8 bit value for the feature length, and
this change broke them (if the code is naive).Signed-off-by: Rusty Russell
Cc: John Cooper
Cc: Christian Borntraeger
12 Jun, 2009
12 commits
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Support the VIRTIO_RING_F_INDIRECT_DESC feature.
This is a simple matter of changing the descriptor walking
code to operate on a struct vring_desc* and supplying it
with an indirect table if detected.Signed-off-by: Mark McLoughlin
Signed-off-by: Rusty Russell -
The Guest only really needs to tell us about activity when we're going
to listen to the eventfd: normally, we don't want to know.So if there are no available buffers, turn on notifications, re-check,
then wait for the Guest to notify us via the eventfd, then turn
notifications off again.There's enough else going on that the differences are in the noise.
Before: Secs RxKicks TxKicks
1G TCP Guest->Host: 3.94 4686 32815
1M normal pings: 104 142862 1000010
1M 1k pings (-l 120): 57 142026 1000007After:
1G TCP Guest->Host: 3.76 4691 32811
1M normal pings: 111 142859 997467
1M 1k pings (-l 120): 55 19648 501549Signed-off-by: Rusty Russell
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Rather than triggering an interrupt every time, we only trigger an
interrupt when there are no more incoming packets (or the recv queue
is full).However, the overhead of doing the select to figure this out is
measurable: 1M pings goes from 98 to 104 seconds, and 1G Guest->Host
TCP goes from 3.69 to 3.94 seconds. It's close to the noise though.I tested various timeouts, including reducing it as the number of
pending packets increased, timing a 1 gigabyte TCP send from Guest ->
Host and Host -> Guest (GSO disabled, to increase packet rate).// time tcpblast -o -s 65536 -c 16k 192.168.2.1:9999 > /dev/null
Timeout Guest->Host Pkts/irq Host->Guest Pkts/irq
Before 11.3s 1.0 6.3s 1.0
0 11.7s 1.0 6.6s 23.5
1 17.1s 8.8 8.6s 26.0
1/pending 13.4s 1.9 6.6s 23.8
2/pending 13.6s 2.8 6.6s 24.1
5/pending 14.1s 5.0 6.6s 24.4Signed-off-by: Rusty Russell
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If we track how many buffers we've used, we can tell whether we really
need to interrupt the Guest. This happens as a side effect of
spurious notifications.Spurious notifications happen because it can take a while before the
Host thread wakes up and sets the VRING_USED_F_NO_NOTIFY flag, and
meanwhile the Guest can more notifications.A real fix would be to use wake counts, rather than a suppression
flag, but the practical difference is generally in the noise: the
interrupt is usually coalesced into a pending one anyway so we just
save a system call which isn't clearly measurable.Secs Spurious IRQS
1G TCP Guest->Host: 3.93 58
1M normal pings: 100 72
1M 1k pings (-l 120): 57 492904Signed-off-by: Rusty Russell
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Rather than sending an interrupt on every buffer, we only send an interrupt
when we're about to wait for the Guest to send us a new one. The console
input and network input still send interrupts manually, but the block device,
network and console output queues can simply rely on this logic to send
interrupts to the Guest at the right time.The patch is cluttered by moving trigger_irq() higher in the code.
In practice, two factors make this optimization less interesting:
(1) we often only get one input at a time, even for networking,
(2) triggering an interrupt rapidly tends to get coalesced anyway.Before: Secs RxIRQS TxIRQs
1G TCP Guest->Host: 3.72 32784 32771
1M normal pings: 99 1000004 995541
100,000 1k pings (-l 120): 5 49510 49058After:
1G TCP Guest->Host: 3.69 32809 32769
1M normal pings: 99 1000004 996196
100,000 1k pings (-l 120): 5 52435 52361(Note the interrupt count on 100k pings goes *up*: see next patch).
Signed-off-by: Rusty Russell
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Currently lguest has three threads: the main Launcher thread, a Waker
thread, and a thread for the block device (because synchronous block
was simply too painful to bear).The Waker selects() on all the input file descriptors (eg. stdin, net
devices, pipe to the block thread) and when one becomes readable it calls
into the kernel to kick the Launcher thread out into userspace, which
repeats the poll, services the device(s), and then tells the kernel to
release the Waker before re-entering the kernel to run the Guest.Also, to make a slightly-decent network transmit routine, the Launcher
would suppress further network interrupts while it set a timer: that
signal handler would write to a pipe, which would rouse the Waker
which would prod the Launcher out of the kernel to check the network
device again.Now we can convert all our virtqueues to separate threads: each one has
a separate eventfd for when the Guest pokes the device, and can trigger
interrupts in the Guest directly.The linecount shows how much this simplifies, but to really bring it
home, here's an strace analysis of single Guest->Host ping before:* Guest sends packet, notifies xmit vq, return control to Launcher
* Launcher clears notification flag on xmit ring
* Launcher writes packet to TUN device
writev(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"\366\r\224`\2058\272m\224vf\274\10\0E\0\0T\0\0@\0@\1\265"..., 98}], 2) = 108
* Launcher sets up interrupt for Guest (xmit ring is empty)
write(10, "\2\0\0\0\3\0\0\0", 8) = 0
* Launcher sets up timer for interrupt mitigation
setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 505}}, NULL) = 0
* Launcher re-runs guest
pread64(10, 0xbfa5f4d4, 4, 0) ...
* Waker notices reply packet in tun device (it was in select)
select(12, [0 3 4 6 11], NULL, NULL, NULL) = 1 (in [4])
* Waker kicks Launcher out of guest:
pwrite64(10, "\3\0\0\0\1\0\0\0", 8, 0) = 0
* Launcher returns from running guest:
... = -1 EAGAIN (Resource temporarily unavailable)
* Launcher looks at input fds:
select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 1 (in [4], left {0, 0})
* Launcher reads pong from tun device:
readv(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"\272m\224vf\274\366\r\224`\2058\10\0E\0\0T\364\26\0\0@"..., 1518}], 2) = 108
* Launcher injects guest notification:
write(10, "\2\0\0\0\2\0\0\0", 8) = 0
* Launcher rechecks fds:
select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 0 (Timeout)
* Launcher clears Waker:
pwrite64(10, "\3\0\0\0\0\0\0\0", 8, 0) = 0
* Launcher reruns Guest:
pread64(10, 0xbfa5f4d4, 4, 0) = ? ERESTARTSYS (To be restarted)
* Signal comes in, uses pipe to wake up Launcher:
--- SIGALRM (Alarm clock) @ 0 (0) ---
write(8, "\0", 1) = 1
sigreturn() = ? (mask now [])
* Waker sees write on pipe:
select(12, [0 3 4 6 11], NULL, NULL, NULL) = 1 (in [6])
* Waker kicks Launcher out of Guest:
pwrite64(10, "\3\0\0\0\1\0\0\0", 8, 0) = 0
* Launcher exits from kernel:
pread64(10, 0xbfa5f4d4, 4, 0) = -1 EAGAIN (Resource temporarily unavailable)
* Launcher looks to see what fd woke it:
select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 1 (in [6], left {0, 0})
* Launcher reads timeout fd, sets notification flag on xmit ring
read(6, "\0", 32) = 1
* Launcher rechecks fds:
select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 0 (Timeout)
* Launcher clears Waker:
pwrite64(10, "\3\0\0\0\0\0\0\0", 8, 0) = 0
* Launcher resumes Guest:
pread64(10, "\0p\0\4", 4, 0) ....strace analysis of single Guest->Host ping after:
* Guest sends packet, notifies xmit vq, creates event on eventfd.
* Network xmit thread wakes from read on eventfd:
read(7, "\1\0\0\0\0\0\0\0", 8) = 8
* Network xmit thread writes packet to TUN device
writev(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"J\217\232FI\37j\27\375\276\0\304\10\0E\0\0T\0\0@\0@\1\265"..., 98}], 2) = 108
* Network recv thread wakes up from read on tunfd:
readv(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"j\27\375\276\0\304J\217\232FI\37\10\0E\0\0TiO\0\0@\1\214"..., 1518}], 2) = 108
* Network recv thread sets up interrupt for the Guest
write(6, "\2\0\0\0\2\0\0\0", 8) = 0
* Network recv thread goes back to reading tunfd
13:39:42.460285 readv(4,
* Network xmit thread sets up interrupt for Guest (xmit ring is empty)
write(6, "\2\0\0\0\3\0\0\0", 8) = 0
* Network xmit thread goes back to reading from eventfd
read(7,Signed-off-by: Rusty Russell
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I've never seen it here, but I can't find anywhere that says writev
will write everything.Signed-off-by: Rusty Russell
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The "len" field in the used ring for virtio indicates the number of
bytes *written* to the buffer. This means the guest doesn't have to
zero the buffers in advance as it always knows the used length.Erroneously, the console and network example code puts the length
*read* into that field. The guest ignores it, but it's wrong.Signed-off-by: Rusty Russell
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20887611523e749d99cc7d64ff6c97d27529fbae (lguest: notify on empty) introduced
lguest support for the VIRTIO_F_NOTIFY_ON_EMPTY flag, but in fact it turned on
interrupts all the time.Because we always process one buffer at a time, the inflight count is always 0
when call trigger_irq and so we always ignore VRING_AVAIL_F_NO_INTERRUPT from
the Guest.It should be looking to see if there are more buffers in the Guest's queue:
if it's empty, then we force an interrupt.This makes little difference, since we usually have an empty queue; but
that's the subject of another patch.Signed-off-by: Rusty Russell
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Since the Launcher process runs the Guest, it doesn't have to be very
serious about its barriers: the Guest isn't running while we are (Guest
is UP).Before we change to use threads to service devices, we need to fix this.
Signed-off-by: Rusty Russell
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We hand the /dev/lguest fd everywhere; it's far neater to just make it
a global (it already is, in fact, hidden in the waker_fds struct).Signed-off-by: Rusty Russell
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We can't trust the values in the device descriptor table once the
guest has booted, so keep local copies. They could set them to
strange values then cause us to segv (they're 8 bit values, so they
can't make our pointers go too wild).This becomes more important with the following patches which read them.
Signed-off-by: Rusty Russell
30 Mar, 2009
1 commit
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Impact: barrier correctness in example launcher
I doubt either lguest user will complain about performance.
Reported-by: Christoph Hellwig
Cc: Jens Axboe
Signed-off-by: Rusty Russell
30 Dec, 2008
2 commits
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This patch moves the initial guest page table creation code to the host,
so the launcher keeps working with PAE enabled configs.Signed-off-by: Matias Zabaljauregui
Signed-off-by: Rusty Russell -
This doesn't really matter, since lguest is i386 only at the moment,
but we could actually choose a different value. (lguest doesn't have
a guarenteed ABI).Signed-off-by: Rusty Russell
31 Oct, 2008
1 commit
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Signed-off-by: Rusty Russell
28 Oct, 2008
1 commit
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The Documentation/i386 and Documentation/x86_64 directories and their
contents have been moved into Documentation/x86. Fix references to
those files accordingly.Signed-off-by: Uwe Hermann
Signed-off-by: Randy Dunlap
Signed-off-by: Ingo Molnar
25 Aug, 2008
1 commit
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Signed-off-by: Rusty Russell
12 Aug, 2008
1 commit
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This shows up when trying to bridge:
tap0: received packet with own address as source addressAs Max Krasnyansky points out, there's no reason to give the guest the
same mac address as the TUN device.Signed-off-by: Rusty Russell
Cc: Max Krasnyansky
29 Jul, 2008
10 commits
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lguest uses a Waker process to break it out of the kernel (ie.
actually running the guest) when file descriptor needs attention.Changing this from a process to a thread somewhat simplifies things:
it can directly access the fd_set of things to watch. More
importantly, it means that the Waker can see Guest memory correctly,
so /dev/vring file descriptors will work as anticipated (the
alternative is to actually mmap MAP_SHARED, but you can't do that with
/dev/zero).Signed-off-by: Rusty Russell
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With big packets, 128 entries is a little small.
Guest -> Host 1GB TCP:
Before: 8.43625 seconds xmit 95640 recv 198266 timeout 49771 usec 1252
After: 8.01099 seconds xmit 49200 recv 102263 timeout 26014 usec 2118Signed-off-by: Rusty Russell
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Guest -> Host 1GB TCP:
Before 20.1974 seconds xmit 214510 recv 5 timeout 214491 usec 278
After 8.43625 seconds xmit 95640 recv 198266 timeout 49771 usec 1252Host -> Guest 1GB TCP:
Before: Seconds 9.98854 xmit 172166 recv 5344 timeout 172157 usec 251
After: Seconds 5.72803 xmit 244322 recv 9919 timeout 244302 usec 156Signed-off-by: Rusty Russell
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This warning can happen a lot under load, and it should be warnx not
warn anwyay.Signed-off-by: Rusty Russell
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Since the correct timeout value varies, use a heuristic which adjusts
the timeout depending on how many packets we've seen. This gives
slightly worse results, but doesn't need tweaking when GSO is
introduced.500 usec 19.1887 xmit 561141 recv 1 timeout 559657
Dynamic (278) 20.1974 xmit 214510 recv 5 timeout 214491 usec 278Signed-off-by: Rusty Russell
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virtio_ring has the ability to suppress notifications. This prevents
a guest exit for every packet, but we need to set a timer on packet
receipt to re-check if there were any remaining packets.Here are the times for 1G TCP Guest->Host with different timeout
settings (it matters because the TCP window doesn't grow big enough to
fill the entire buffer):Timeout value Seconds Xmit/Recv/Timeout
None (before) 25.3784 xmit 7750233 recv 1
2500 usec 62.5119 xmit 207020 recv 2 timeout 207020
1000 usec 34.5379 xmit 207003 recv 2 timeout 207003
750 usec 29.2305 xmit 207002 recv 1 timeout 207002
500 usec 19.1887 xmit 561141 recv 1 timeout 559657
250 usec 20.0465 xmit 214128 recv 2 timeout 214110
100 usec 19.2583 xmit 561621 recv 1 timeout 560153(Note that these values are sensitive to the GSO patches which come
later, and probably other traffic-related variables, so take with a
large grain of salt).Signed-off-by: Rusty Russell
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Number of exits transmitting 10GB Guest->Host before:
network xmit 7858610 recv 118136After:
network xmit 7750233 recv 1Signed-off-by: Rusty Russell
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To simplify the transition to when we publish indices in the ring
(and make shuffling my patch queue easier), wrap them in a lg_last_avail()
macro.Signed-off-by: Rusty Russell
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This is a simple patch to add support for the virtio "hardware random
generator" to lguest. It gets about 1.2 MB/sec reading from /dev/hwrng
in the guest.Signed-off-by: Rusty Russell
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If you've got a nice DHCP configuration which maps MAC
addresses to specific IP addresses, then you're going to
want to start your guest with one of those MAC addresses.Also, in Fedora, we have persistent network interface naming
based on the MAC address, so with randomly assigned
addresses you're soon going to hit eth13. Who knows what
will happen then!Allow assigning a MAC address to the network interface with
e.g.--tunnet=bridge:eth0:00:FF:95:6B:DA:3D
or:
--tunnet=192.168.121.1:00:FF:95:6B:DA:3D
which is pretty unintelligable, but ...
(includes Rusty's minor rework)
Signed-off-by: Mark McLoughlin
Signed-off-by: Rusty Russell