Re: [PULL v2 0/5] 9p queue (previous 2020-10-15)

From: Christian Schoenebeck <qemu_oss@crudebyte.com>
To: qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Greg Kurz <groug@kaod.org>
Subject: Re: [PULL v2 0/5] 9p queue (previous 2020-10-15)
Date: Mon, 19 Oct 2020 12:19:11 +0200	[thread overview]
Message-ID: <3061113.rifjho4eKY@silver> (raw)
In-Reply-To: <CAFEAcA8M2n9X0a2bzcc-bZTvh8cMYrQ39mWLUzNAJzkgNe8UFw@mail.gmail.com>

On Montag, 19. Oktober 2020 11:52:38 CEST Peter Maydell wrote:
> On Sat, 17 Oct 2020 at 15:23, Christian Schoenebeck
> 
> <qemu_oss@crudebyte.com> wrote:
> > The following changes since commit 
e12ce85b2c79d83a340953291912875c30b3af06:
> >   Merge remote-tracking branch
> >   'remotes/ehabkost/tags/x86-next-pull-request' into staging (2020-10-16
> >   22:46:28 +0100)> 
> > are available in the Git repository at:
> >   https://github.com/cschoenebeck/qemu.git tags/pull-9p-20201017
> > 
> > for you to fetch changes up to fa4551e3f4416cc8c62086ac430b1ceb4f03eb6b:
> >   tests/9pfs: add local Tmkdir test (2020-10-17 15:58:39 +0200)
> > 
> > ----------------------------------------------------------------
> > 9pfs: add tests using local fs driver
> > 
> > The currently existing 9pfs test cases are all solely using the 9pfs
> > 'synth' fileystem driver, which is a very simple and purely simulated (in
> > RAM only) filesystem. There are issues though where the 'synth' fs driver
> > is not sufficient. For example the following two bugs need test cases
> > running the 9pfs 'local' fs driver:
> > 
> > https://bugs.launchpad.net/qemu/+bug/1336794
> > https://bugs.launchpad.net/qemu/+bug/1877384
> > 
> > This patch set for that reason introduces 9pfs test cases using the 9pfs
> > 'local' filesystem driver along to the already existing tests on 'synth'.
> 
> This emits a lot of new warnings during 'make check':
> 
> PASS 27 qtest-arm: qos-test
> /arm/virt/virtio-mmio/virtio-bus/virtio-9p-device/virtio-9p/virtio-9p-tests/
> local/config qemu-system-arm: warning: 9p: degraded performance: a
> reasonable high msize should be chosen on client/guest side (chosen msize
> is <= 8192). See https://wiki.qemu.org/Documentation/9psetup#msize for
> details. PASS 28 qtest-arm: qos-test
> /arm/virt/virtio-mmio/virtio-bus/virtio-9p-device/virtio-9p/virtio-9p-tests/
> local/create_dir
> 
> PASS 54 qtest-i386: qos-test
> /i386/pc/i440FX-pcihost/pci-bus-pc/pci-bus/virtio-9p-pci/virtio-9p/virtio-9p
> -tests/local/config qemu-system-i386: warning: 9p: degraded performance: a
> reasonable high msize should be chosen on client/guest side (chosen msize
> is <= 8192). See https://wiki.qemu.org/Documentation/9psetup#msize for
> details. PASS 55 qtest-i386: qos-test
> /i386/pc/i440FX-pcihost/pci-bus-pc/pci-bus/virtio-9p-pci/virtio-9p/virtio-9p
> -tests/local/create_dir
> 
> etc.
> 
> thanks
> -- PMM

One warning per test suite run (i.e. per architecture due to 
warn_report_once()), yes. That performance warning is meant for end user 
installations to remind them setting some (reasonable high) value for 9p 
client parameter 'msize' on guest OS side. The warning triggers here because 
the 9p test cases intentionally run with a small 'msize' to guard edge cases.

Would it be Ok for you to merge it with this performance warning for now? I 
can take care of silencing it before 5.2 release. It probably requires to 
introduce a new CL option to suppress performance warnings like these, or by 
finding a way to detect that we're currently just running qtests.

Best regards,
Christian Schoenebeck