In certain circumstances, posix-aio-compat can incur a lot of latency:
- threads are created by vcpu threads, so if vcpu affinity is set,
aio threads inherit vcpu affinity. This can cause many aio threads
to compete for one cpu.
- we can create up to max_threads (64) aio threads in one go; since a
pthread_create can take around 30μs, we have up to 2ms of cpu time
under a global lock.
Fix by:
- moving thread creation to the main thread, so we inherit the main
thread's affinity instead of the vcpu thread's affinity.
- if a thread is currently being created, and we need to create yet
another thread, let thread being born create the new thread, reducing
the amount of time we spend under the main thread.
- drop the local lock while creating a thread (we may still hold the
global mutex, though)
Note this doesn't eliminate latency completely; scheduler artifacts or
lack of host cpu resources can still cause it. We may want pre-allocated
threads when this cannot be tolerated.
Thanks to Uli Obergfell of Red Hat for his excellent analysis and suggestions.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Current behaviour if a read fails is for the acb to not get finished.
This causes an infinite loop in bdrv_read_em (block.c). The read failure
never gets reported to the guest and if the error condition clears, the
process never recovers.
With this patch, when curl reports a failure we finish the acb as a
failure. This results in the guest receiving an I/O error (rather than
the read hanging indefinitely) and if the error condition subsequently
clears, retries work as expected.
The simplest test is to put an ISO on a web server you have control over
and open it with qemu-io. Then move the ISO out of the way and attempt
to read some data - you should see behaviour matching the above.
Signed-off-by: Nick Thomas <nick@bytemark.co.uk>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
commit 52b8eb6013 added a mutex,
but never initialized it. This caused a segfault.
Reported-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Documentation states the num is measured in clusters, but its
actually measured in sectors
Signed-off-by: Devin Nakamura <devin122@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Now that you can use cache=none for the output file in qemu-img, we should
properly align our buffers so that raw-posix doesn't have to use its (smaller)
bounce buffer.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
By introducing BlockDriverState compiling qcow2 with DEBUG_ALLOC and DEBUG_EXT
defined got broken.
Define a BdrvCheckResult structure locally which is now needed as the second
argument.
Also fix qcow2_read_extensions() needing BDRVQcowState.
Signed-off-by: Philipp Hahn <hahn@univention.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch adds -drive cache=directsync for O_DIRECT | O_SYNC host file
I/O with no disk write cache presented to the guest.
This mode is useful when guests may not be sending flushes when
appropriate and therefore leave data at risk in case of power failure.
When cache=directsync is used, write operations are only completed to
the guest when data is safely on disk.
This new mode is like cache=writethrough but it bypasses the host page
cache.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch introduces bdrv_parse_cache_flags() which sets open flags
given a cache mode. Previously this was duplicated in blockdev.c and
qemu-img.c.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This is a microblaze target specific function that belongs outside
of xilinx.h (which is a collection of target independent device model
instantiator functions)
Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Added some missing #includes for this file. Previously this file
relied on its clients to pre-include its dependencies.
Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
While in full-screen mode, the input focus naturally belongs to the SDL
window. Avoid dropping it when switching from absolute to relative
mouse mode.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
We can express the VCPU thread wakeup with the stop mechanism, saving
both qemu_system_ready and the qemu_system_cond. For KVM threads, we can
just enter the main loop as long as the thread is stopped. The central
TCG thread is better held back before the loop as there can be side
effects of the services called even when all CPUs are stopped.
Creating VCPUs in stopped state will also be required for proper CPU
hotplugging support.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Memory region refactorings obsoleted them.
CC: Avi Kivity <avi@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Most VGA memory access modes require MMIO handling as they demand weird
logic to get a byte from or into the video RAM. However, there is one
exception: chain 4 mode with all memory planes enabled for writing. This
mode actually allows lineary mapping, which can then be combined with
dirty logging to accelerate KVM.
This patch accelerates specifically VBE accesses like they are used by
grub in graphical mode. Not only the standard VGA adapter benefits from
this, also vmware and spice in VGA mode.
CC: Gerd Hoffmann <kraxel@redhat.com>
CC: Avi Kivity <avi@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
After the conversion to the new Memory API, vga_dirty_log_restart became
seriously pointless. Remove it from vmware-vga and and then finally drop
the service.
CC: Andrzej Zaborowski <balrogg@gmail.com>
CC: Avi Kivity <avi@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The code was disabled since day 1 of vmware-vga, and now it does not
even build anymore. Time for a cleanup.
CC: Andrzej Zaborowski <balrogg@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Elimiates 'vmsvga_value_write: guest runs Linux.' messages from the
console.
CC: Andrzej Zaborowski <balrogg@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Fixes cold reset in vmware graphic modes. We need to split up the reset
function for this purpose, breaking out init-once bits.
Cc: Andrzej Zaborowski <balrogg@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
If the polarity bit is set in the redirection table, the input level
simply has to inverted as it is low active in this case.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Polarity of external interrupts needs to be handled in the IOAPIC.
Passing it to the APIC is pointless. So remove all these arguments.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
In TCG mode, iothread and vcpus run in lock-step. So it's pointless to
send a signal from qemu_cpu_kick to the vcpu thread - if we got here,
the receiver already left the vcpu loop.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Polling until select returns empty fdsets helps to reduce the switches
between iothread and vcpus. The benefit of this patch is best visible
when running an SMP guest on an SMP host in emulation mode.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
If we call select without a timeout, it's more efficient to keep the
global mutex locked as we may otherwise just play ping pong with a
vcpu thread contending for it. This is particularly important for TCG
mode where we run in lock-step with the vcpu thread.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The legacy functions that we're wrapping expect that offset
to be included in the register. Indeed, they generally
expect the absolute address and then mask off the "high" bits.
The FDC is the first converted device with a non-zero offset.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Avi Kivity <avi@redhat.com>
After 312b4234, the APIC and PCI devices are colliding with each other. This
is harmless in practice because the APIC accesses are special cased and never
make there way onto the bus.
Avi is working on a proper fix, but until that's ready, avoid printing the
warning.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The current implementation of PAM and the PCI holes is broken in several
ways:
- PCI BARs are not restricted to the PCI hole (a BAR may hide memory)
- PCI devices do not respect PAM (if a PCI device maps a region while
PAM maps the region to RAM, the request will be honored)
This patch fixes things by introducing a pci address space, and using
memory region aliases to represent PAM regions, SMRAM, and PCI holes.
The memory hierarchy looks something like
system_memory
|
+--- low memory alias (0-0xe0000000)
| |
| +-- ram@0
|
+--- high memory alias (0x100000000-EOM)
| |
| +-- ram@0xe0000000
|
+--- pci hole alias (end of low memory-0x100000000)
| |
| +-- pci@end-of-low-memory
|
|
+--- pam[n] (0xc0000-0xc3fff etc) (when set to pci, priority 1)
| |
| +-- pci@0xc4000 etc
|
+--- smram (0xa0000-0xbffff) (when set to pci/vga, priority 1)
|
+-- pci@0xa0000 etc
ram (simple ram region)
pci
|
+--- BARn
|
+--- VGA 0xa0000-0xbffff
|
+--- ROMs
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Instead, use the bus accessors, or get the address space directly
from the board constructor.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Returns the PCI address space. Useful for bridges that can obscure
part of the PCI address space.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
A helper that returns the address space used by ISA devices. Useful
for getting rid of isa_mem_base, multiple ISA buses, or ISA buses behind
bridges.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This problem with this function is that it is not reversible - it is
impossible to know where things are registered and unregister them
exactly. As there are no more users, we can remove it.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Not a huge step forward, but at least we now have a 1:1 relationship
between registration and unregistration.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This tells the sysbus code it need not use IO_MEM_UNASSIGNED.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
sysbus_init_mmio_cb() uses the destructive IO_MEM_UNASSIGNED to remove a
region. Provide an alternative that calls an unmap callback, so the removal
may be done non-destructively.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Clumsy due to the lack of clipping support, needed for
changing exposed ram size.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Somewhat clumsy since it needs a variable sized region.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
