The thread pool regulates itself: when idle, it kills threads until
empty, when in demand, it creates new threads until full. This behaviour
doesn't play well with latency sensitive workloads where the price of
creating a new thread is too high. For example, when paired with qemu's
'-mlock', or using safety features like SafeStack, creating a new thread
has been measured take multiple milliseconds.
In order to mitigate this let's introduce a new 'EventLoopBase'
property to set the thread pool size. The threads will be created during
the pool's initialization or upon updating the property's value, remain
available during its lifetime regardless of demand, and destroyed upon
freeing it. A properly characterized workload will then be able to
configure the pool to avoid any latency spikes.
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-4-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
'event-loop-base' provides basic property handling for all 'AioContext'
based event loops. So let's define a new 'MainLoopClass' that inherits
from it. This will permit tweaking the main loop's properties through
qapi as well as through the command line using the '-object' keyword[1].
Only one instance of 'MainLoopClass' might be created at any time.
'EventLoopBaseClass' learns a new callback, 'can_be_deleted()' so as to
mark 'MainLoop' as non-deletable.
[1] For example:
-object main-loop,id=main-loop,aio-max-batch=<value>
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-3-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Introduce the 'event-loop-base' abstract class, it'll hold the
properties common to all event loops and provide the necessary hooks for
their creation and maintenance. Then have iothread inherit from it.
EventLoopBaseClass is defined as user creatable and provides a hook for
its children to attach themselves to the user creatable class 'complete'
function. It also provides an update_params() callback to propagate
property changes onto its children.
The new 'event-loop-base' class will live in the root directory. It is
built on its own using the 'link_whole' option (there are no direct
function dependencies between the class and its children, it all happens
trough 'constructor' magic). And also imposes new compilation
dependencies:
qom <- event-loop-base <- blockdev (iothread.c)
And in subsequent patches:
qom <- event-loop-base <- qemuutil (util/main-loop.c)
All this forced some amount of reordering in meson.build:
- Moved qom build definition before qemuutil. Doing it the other way
around (i.e. moving qemuutil after qom) isn't possible as a lot of
core libraries that live in between the two depend on it.
- Process the 'hw' subdir earlier, as it introduces files into the
'qom' source set.
No functional changes intended.
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-2-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
qemu-sparc queue
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# gpg: Signature made Sun 08 May 2022 12:53:43 PM CDT
# gpg: using RSA key CC621AB98E82200D915CC9C45BC2C56FAE0F321F
# gpg: issuer "mark.cave-ayland@ilande.co.uk"
# gpg: Good signature from "Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>" [undefined]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: CC62 1AB9 8E82 200D 915C C9C4 5BC2 C56F AE0F 321F
* tag 'qemu-sparc-20220508' of https://github.com/mcayland/qemu: (53 commits)
artist: only render dirty scanlines on the display surface
artist: remove unused ROP8OFF() macro
artist: checkpatch and newline style fixes
hppa: simplify machine function names in machine.c
hppa: fold machine_hppa_machine_init() into machine_hppa_machine_init_class_init()
hppa: use MACHINE QOM macros for defining the hppa machine
hppa: remove the empty hppa_sys.h file
hppa: move enable_lan() define from hppa_sys.h to machine.c
hppa: remove unused trace-events from from hw/hppa
hppa: remove hw/hppa/pci.c
hppa: move hppa_pci_ignore_ops from pci.c to machine.c
lasi: move from hw/hppa to hw/misc
hppa: move device headers from hppa_sys.h into individual .c files
lasi: use numerical constant for iar reset value
lasi: use constants for device register offsets
lasi: move lasi_initfn() to machine.c
lasi: remove address space parameter from lasi_initfn()
lasi: move PS2 initialisation to machine.c
lasi: move second serial port initialisation to machine.c
lasi: move parallel port initialisation to machine.c
...
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The framebuffer_update_display() function returns the dirty scanlines that were
touched since the last display update, however artist_update_display() always calls
dpy_gfx_update() with start and end scanlines of 0 and s->height causing the
entire display surface to be rendered on every update.
Update artist_update_display() so that dpy_gfx_update() only renders the dirty
scanlines on the display surface, bypassing the display surface rendering
completely if framebuffer_update_display() indicates no changes occurred.
This noticeably improves boot performance when the framebuffer is enabled on my
rather modest laptop here, including making the GTK UI usable.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220504153708.10352-4-mark.cave-ayland@ilande.co.uk>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
DINO refers to the GSC-PCI bridge device which will soon be handled separately,
however the QEMU HPPA machine is actually based upon the HPPA B160L as indicated
by the Linux kernel dmesg output when booted in qemu-system-hppa and the QEMU
MAINTAINERS file.
Update the machine configuration to use CONFIG_HPPA_B160L instead of CONFIG_DINO
and also update the machine description accordingly.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Helge Deller <deller@gmx.de>
Message-Id: <20220504092600.10048-13-mark.cave-ayland@ilande.co.uk>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
