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  1. 13 6月, 2009 25 次提交
  3. 12 6月, 2009 15 次提交
    • P
      slab: setup cpu caches later on when interrupts are enabled · 8429db5c
      由 Pekka Enberg 提交于 
      Fixes the following boot-time warning:

  [    0.000000] ------------[ cut here ]------------
  [    0.000000] WARNING: at kernel/smp.c:369 smp_call_function_many+0x56/0x1bc()
  [    0.000000] Hardware name:
  [    0.000000] Modules linked in:
  [    0.000000] Pid: 0, comm: swapper Not tainted 2.6.30 #492
  [    0.000000] Call Trace:
  [    0.000000]  [<ffffffff8149e021>] ? _spin_unlock+0x4f/0x5c
  [    0.000000]  [<ffffffff8108f11b>] ? smp_call_function_many+0x56/0x1bc
  [    0.000000]  [<ffffffff81061764>] warn_slowpath_common+0x7c/0xa9
  [    0.000000]  [<ffffffff810617a5>] warn_slowpath_null+0x14/0x16
  [    0.000000]  [<ffffffff8108f11b>] smp_call_function_many+0x56/0x1bc
  [    0.000000]  [<ffffffff810f3e00>] ? do_ccupdate_local+0x0/0x54
  [    0.000000]  [<ffffffff810f3e00>] ? do_ccupdate_local+0x0/0x54
  [    0.000000]  [<ffffffff8108f2be>] smp_call_function+0x3d/0x68
  [    0.000000]  [<ffffffff810f3e00>] ? do_ccupdate_local+0x0/0x54
  [    0.000000]  [<ffffffff81066fd8>] on_each_cpu+0x31/0x7c
  [    0.000000]  [<ffffffff810f64f5>] do_tune_cpucache+0x119/0x454
  [    0.000000]  [<ffffffff81087080>] ? lockdep_init_map+0x94/0x10b
  [    0.000000]  [<ffffffff818133b0>] ? kmem_cache_init+0x421/0x593
  [    0.000000]  [<ffffffff810f69cf>] enable_cpucache+0x68/0xad
  [    0.000000]  [<ffffffff818133c3>] kmem_cache_init+0x434/0x593
  [    0.000000]  [<ffffffff8180987c>] ? mem_init+0x156/0x161
  [    0.000000]  [<ffffffff817f8aae>] start_kernel+0x1cc/0x3b9
  [    0.000000]  [<ffffffff817f829a>] x86_64_start_reservations+0xaa/0xae
  [    0.000000]  [<ffffffff817f837f>] x86_64_start_kernel+0xe1/0xe8
  [    0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---

Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
      8429db5c
    • P
      slab,slub: don't enable interrupts during early boot · 7e85ee0c
      由 Pekka Enberg 提交于 
      As explained by Benjamin Herrenschmidt:

  Oh and btw, your patch alone doesn't fix powerpc, because it's missing
  a whole bunch of GFP_KERNEL's in the arch code... You would have to
  grep the entire kernel for things that check slab_is_available() and
  even then you'll be missing some.

  For example, slab_is_available() didn't always exist, and so in the
  early days on powerpc, we used a mem_init_done global that is set form
  mem_init() (not perfect but works in practice). And we still have code
  using that to do the test.

Therefore, mask out __GFP_WAIT, __GFP_IO, and __GFP_FS in the slab allocators
in early boot code to avoid enabling interrupts.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
      7e85ee0c
    • P
      slab: fix gfp flag in setup_cpu_cache() · eb91f1d0
      由 Pekka Enberg 提交于 
      Fixes the following warning during bootup when compiling with CONFIG_SLAB:

  [    0.000000] ------------[ cut here ]------------
  [    0.000000] WARNING: at kernel/lockdep.c:2282 lockdep_trace_alloc+0x91/0xb9()
  [    0.000000] Hardware name:
  [    0.000000] Modules linked in:
  [    0.000000] Pid: 0, comm: swapper Not tainted 2.6.30 #491
  [    0.000000] Call Trace:
  [    0.000000]  [<ffffffff81087d84>] ? lockdep_trace_alloc+0x91/0xb9
  [    0.000000]  [<ffffffff81061764>] warn_slowpath_common+0x7c/0xa9
  [    0.000000]  [<ffffffff810617a5>] warn_slowpath_null+0x14/0x16
  [    0.000000]  [<ffffffff81087d84>] lockdep_trace_alloc+0x91/0xb9
  [    0.000000]  [<ffffffff810f5b03>] kmem_cache_alloc_node_notrace+0x26/0xdf
  [    0.000000]  [<ffffffff81487f4e>] ? setup_cpu_cache+0x7e/0x210
  [    0.000000]  [<ffffffff81487fe3>] setup_cpu_cache+0x113/0x210
  [    0.000000]  [<ffffffff810f73ff>] kmem_cache_create+0x409/0x486
  [    0.000000]  [<ffffffff818131c1>] kmem_cache_init+0x232/0x593
  [    0.000000]  [<ffffffff8180987c>] ? mem_init+0x156/0x161
  [    0.000000]  [<ffffffff817f8aae>] start_kernel+0x1cc/0x3b9
  [    0.000000]  [<ffffffff817f829a>] x86_64_start_reservations+0xaa/0xae
  [    0.000000]  [<ffffffff817f837f>] x86_64_start_kernel+0xe1/0xe8
  [    0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
      eb91f1d0
    • J
      [SCSI] Merge branch 'linus' · 82681a31
      由 James Bottomley 提交于 
      Conflicts:
	drivers/message/fusion/mptsas.c

fixed up conflict between req->data_len accessors and mptsas driver updates.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
      82681a31
    • M
      lguest: add support for indirect ring entries · d1f0132e
      由 Mark McLoughlin 提交于 
      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: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      d1f0132e
    • R
      lguest: suppress notifications in example Launcher · b60da13f
      由 Rusty Russell 提交于 
      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	1000007

After:
 1G TCP Guest->Host:		3.76	  4691	  32811
 1M normal pings:		111	142859	 997467
 1M 1k pings (-l 120):		55	 19648	 501549
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      b60da13f
    • R
      lguest: try to batch interrupts on network receive · 4a8962e2
      由 Rusty Russell 提交于 
      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		24.4
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      4a8962e2
    • R
      lguest: avoid sending interrupts to Guest when no activity occurs. · 95c517c0
      由 Rusty Russell 提交于 
      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	492904
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      95c517c0
    • R
      lguest: implement deferred interrupts in example Launcher · 38bc2b8c
      由 Rusty Russell 提交于 
      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	49058

After:
 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: NRusty Russell <rusty@rustcorp.com.au>
      38bc2b8c
    • R
      lguest: remove obsolete LHREQ_BREAK call · 5dac051b
      由 Rusty Russell 提交于 
      We no longer need an efficient mechanism to force the Guest back into
host userspace, as each device is serviced without bothering the main
Guest process (aka. the Launcher).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      5dac051b
    • R
      lguest: have example Launcher service all devices in separate threads · 659a0e66
      由 Rusty Russell 提交于 
      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,  <unfinished ...>
* 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, <unfinished ...>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      659a0e66
    • R
      lguest: use eventfds for device notification · df60aeef
      由 Rusty Russell 提交于 
      Currently, when a Guest wants to perform I/O it calls LHCALL_NOTIFY with
an address: the main Launcher process returns with this address, and figures
out what device to run.

A far nicer model is to let processes bind an eventfd to an address: if we
find one, we simply signal the eventfd.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Davide Libenzi <davidel@xmailserver.org>
      df60aeef
    • R
      eventfd: export eventfd_signal and eventfd_fget for lguest · 5718607b
      由 Rusty Russell 提交于 
      lguest wants to attach eventfds to guest notifications, and lguest is
usually a module.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
To: Davide Libenzi <davidel@xmailserver.org>
      5718607b
    • R
      lguest: allow any process to send interrupts · 9f155a9b
      由 Rusty Russell 提交于 
      We currently only allow the Launcher process to send interrupts, but it
as we already send interrupts from the hrtimer, it's a simple matter of
extracting that code into a common set_interrupt routine.

As we switch to a thread per virtqueue, this avoids a bottleneck through the
main Launcher process.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      9f155a9b
    • R
      lguest: PAE fixes · 92b4d8df
      由 Rusty Russell 提交于 
      1) j wasn't initialized in setup_pagetables, so they weren't set up for me
   causing immediate guest crashes.

2) gpte_addr should not re-read the pmd from the Guest.  Especially
   not BUG_ON() based on the value.  If we ever supported SMP guests,
   they could trigger that.  And the Launcher could also trigger it
   (tho currently root-only).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      92b4d8df