From: Paolo Bonzini <pbonzini@redhat.com>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>, qemu-devel@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
qemu-block@nongnu.org, "Corey Minyard" <minyard@acm.org>,
"David Hildenbrand" <david@redhat.com>,
"Andrew Jeffery" <andrew@aj.id.au>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Max Reitz" <mreitz@redhat.com>,
qemu-arm@nongnu.org, "Joel Stanley" <joel@jms.id.au>,
"Cédric Le Goater" <clg@kaod.org>
Subject: Re: [PATCH 0/7] misc: Reduce QEMUTimer pressure by using lower precision when possible
Date: Thu, 18 Jun 2020 14:42:18 +0200 [thread overview]
Message-ID: <80230616-1927-e861-98f5-b9aaf2fe03b7@redhat.com> (raw)
In-Reply-To: <df330613-a75a-5d3c-5290-c080f5c32785@amsat.org>
On 18/06/20 14:26, Philippe Mathieu-Daudé wrote:
>> This is in principle a very good idea; however, util/qemu-timer.c does
>> not use the scale to coalesce low-precision timers with nearby
>> high-precision ones.
> IOW this doesn't reduce the pressure, but simply makes the code easier?
Easier, or harder depending on the point of view. The reason why scale
exists is just because QEMU_CLOCK_REALTIME used to be millisecond based;
having to scale based on the clock was really ugly code, and furthermore
the scale provides an easy way to switch timers from one clock to
another without having to modify every deadline computation.
One might argue that the scale adds to QEMU's cognitive weight for
little benefit. You might counter-argue that having to scale up to
nanoseconds every time is a pain in the ass, and I am not sure which
side I actually agree with.
> Only the cover mentions 'pressure', so maybe the patches can still be
> reviewed/queued in their current state?
Yes, of course.
Paolo
next prev parent reply other threads:[~2020-06-18 12:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 7:51 [PATCH 0/7] misc: Reduce QEMUTimer pressure by using lower precision when possible Philippe Mathieu-Daudé
2020-06-16 7:51 ` [PATCH 1/7] qemu-common: Briefly document qemu_timedate_diff() unit Philippe Mathieu-Daudé
2020-06-18 5:47 ` Markus Armbruster
2020-06-22 8:50 ` Philippe Mathieu-Daudé
2020-06-16 7:51 ` [PATCH 2/7] block/qcow2: Document cache_clean_interval field holds seconds Philippe Mathieu-Daudé
2020-06-16 7:51 ` [PATCH 3/7] block/curl: Reduce timer precision to milli-second Philippe Mathieu-Daudé
2020-06-16 7:51 ` [PATCH 4/7] hw/virtio/virtio-balloon: Rename timer field including 'ms' unit Philippe Mathieu-Daudé
2020-06-16 7:57 ` David Hildenbrand
2020-06-16 7:51 ` [PATCH 5/7] hw/rtc/m48t59: Reduce timer precision to milli-second Philippe Mathieu-Daudé
2020-07-08 23:39 ` Richard Henderson
2020-06-16 7:51 ` [PATCH 6/7] hw/ipmi/ipmi_bmc_extern: " Philippe Mathieu-Daudé
2020-06-16 7:51 ` [PATCH 7/7] hw/watchdog/wdt_aspeed: Reduce timer precision to micro-second Philippe Mathieu-Daudé
2020-06-17 1:18 ` Andrew Jeffery
2020-06-17 3:41 ` Philippe Mathieu-Daudé
2020-06-22 0:21 ` Andrew Jeffery
2020-06-22 8:43 ` Philippe Mathieu-Daudé
2020-06-22 23:45 ` Andrew Jeffery
2020-07-08 23:40 ` Richard Henderson
2020-06-18 12:23 ` [PATCH 0/7] misc: Reduce QEMUTimer pressure by using lower precision when possible Paolo Bonzini
2020-06-18 12:26 ` Philippe Mathieu-Daudé
2020-06-18 12:42 ` Paolo Bonzini [this message]
2020-07-08 23:37 ` Richard Henderson
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