From: Richard Henderson <richard.henderson@linaro.org>
To: "Daniel P. Berrangé" <berrange@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>
Cc: fam@euphon.net, qemu-devel@nongnu.org,
Christian Ehrhardt <christian.ehrhardt@canonical.com>,
f4bug@amsat.org, cota@braap.org,
Paolo Bonzini <pbonzini@redhat.com>,
aurelien@aurel32.net, Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH v2 06/12] accel/tcg: better handle memory constrained systems
Date: Wed, 22 Jul 2020 12:02:59 -0700 [thread overview]
Message-ID: <0efbcac2-d2f4-de96-63a1-ba7cd485a1e6@linaro.org> (raw)
In-Reply-To: <20200722163722.GS2324845@redhat.com>
On 7/22/20 9:44 AM, Daniel P. Berrangé wrote:
> OpenStack uses TCG in alot of their CI infrastructure for example
> and runs multiple VMs. If there's 4 VMs, that's another 4 GB of
> RAM usage just silently added on top of the explicit -m value.
>
> I wouldn't be surprised if this pushes CI into OOM, even without
> containers or cgroups being involved, as they have plenty of other
> services consuming RAM in the CI VMs.
I would hope that CI would also supply a -tb_size to go along with that -m
value. Because we really can't guess on their behalf.
> The commit 600e17b261555c56a048781b8dd5ba3985650013 talks about this
> minimizing codegen cache flushes, but doesn't mention the real world
> performance impact of eliminating those flushes ?
Somewhere on the mailing list was this info. It was so dreadfully slow it was
*really* noticable. Timeouts everywhere.
>
> Presumably this makes the guest OS boot faster, but what's the before
> and after time ? And what's the time like for values in between the
> original 32mb and the new 1 GB ?
But it wasn't "the original 32MB".
It was the original "ram_size / 4", until that broke due to argument parsing
ordering.
I don't know what CI usually uses, but I usually use at least -m 4G, sometimes
more. What's the libvirt default?
r~
next prev parent reply other threads:[~2020-07-22 19:03 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 6:28 [PATCH v2 00/12] candidate fixes for 5.1-rc1 (testing, semihosting, OOM tcg, x86 fpu) Alex Bennée
2020-07-22 6:28 ` [PATCH v2 01/12] shippable: add one more qemu to registry url Alex Bennée
2020-07-22 6:28 ` [PATCH v2 02/12] semihosting: defer connect_chardevs a little more to use serialx Alex Bennée
2020-07-22 6:28 ` [PATCH v2 03/12] semihosting: don't send the trailing '\0' Alex Bennée
2020-07-22 6:28 ` [PATCH v2 04/12] util: add qemu_get_host_physmem utility function Alex Bennée
2020-07-22 15:51 ` Richard Henderson
2020-07-22 6:28 ` [PATCH v2 05/12] util/oslib-win32: add qemu_get_host_physmem implementation Alex Bennée
2020-07-22 6:49 ` Philippe Mathieu-Daudé
2020-07-22 10:03 ` Stefan Weil
2020-07-22 10:13 ` Daniel P. Berrangé
2020-07-22 11:33 ` Alex Bennée
2020-07-22 11:38 ` Daniel P. Berrangé
2020-07-22 10:32 ` 罗勇刚(Yonggang Luo)
2020-07-22 10:50 ` Stefan Weil
2020-07-22 11:31 ` Alex Bennée
2020-07-22 11:41 ` Daniel P. Berrangé
2020-07-22 6:28 ` [PATCH v2 06/12] accel/tcg: better handle memory constrained systems Alex Bennée
2020-07-22 15:57 ` Richard Henderson
2020-07-22 16:29 ` Alex Bennée
2020-07-22 16:44 ` Daniel P. Berrangé
2020-07-22 19:02 ` Richard Henderson [this message]
2020-07-23 9:00 ` Daniel P. Berrangé
2020-07-23 9:22 ` Alex Bennée
2020-07-23 9:31 ` Daniel P. Berrangé
2020-07-23 10:06 ` Alex Bennée
2020-07-22 6:28 ` [PATCH v2 07/12] target/i386: floatx80: avoid compound literals in static initializers Alex Bennée
2020-07-22 6:45 ` Philippe Mathieu-Daudé
2020-07-22 6:28 ` [PATCH v2 08/12] linux-user: don't use MAP_FIXED in pgd_find_hole_fallback Alex Bennée
2020-07-22 16:00 ` Richard Henderson
2020-07-22 6:28 ` [PATCH v2 09/12] tests/docker: fix update command due to python3 str/bytes distinction Alex Bennée
2020-07-22 6:29 ` [PATCH v2 10/12] tests/docker: fix binfmt_misc image building Alex Bennée
2020-07-22 6:35 ` Philippe Mathieu-Daudé
2020-07-22 6:29 ` [PATCH v2 11/12] tests/docker: add support for DEB_KEYRING Alex Bennée
2020-07-22 14:27 ` Philippe Mathieu-Daudé
2020-07-22 16:03 ` Richard Henderson
2020-07-22 6:29 ` [PATCH v2 12/12] linux-user: fix clock_nanosleep() Alex Bennée
2020-07-22 6:49 ` Laurent Vivier
2020-07-22 8:33 ` Laurent Vivier
2020-07-22 8:55 ` Alex Bennée
2020-07-22 12:03 ` Laurent Vivier
2020-07-22 7:05 ` Philippe Mathieu-Daudé
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