From: Ali Saidi <alisaidi@amazon.com>
To: <kjlx@templeofstupid.com>
Cc: <alisaidi@amazon.com>, <catalin.marinas@arm.com>,
<james.morse@arm.com>, <kvmarm@lists.linux.dev>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <maz@kernel.org>,
<me@davidreaver.com>, <oliver.upton@linux.dev>,
<suzuki.poulose@arm.com>, <will@kernel.org>,
<yuzenghui@huawei.com>
Subject: Re: [PATCH] KVM: arm64: Limit stage2_apply_range() batch size to smallest block
Date: Thu, 4 Apr 2024 21:27:42 +0000 [thread overview]
Message-ID: <20240404212742.11248-1-alisaidi@amazon.com> (raw)
In-Reply-To: <20240404044028.GA1976@templeofstupid.com>
I measured the time it takes to unmap a VM by changing the kvm_page_table_test
to report it. It's and on Graviton3 it's about 300ms per 1GB of flushing
with 4KB pages. Unmapping 128GB takes around 39.5s and with a single call to
__kvm_tlb_flush_vmid() instead of the 32M calls to __kvm_tlb_flush_vmid_ipa()
reduces this to around 5.9s (~7x). This means each iteration of the
stage2_apply_range() is reduced to 46ms. So we're certainly calling
cond_resched() a whole lot more.
> Just a quick followup that I did test Will's patches and didn't find
> that it changed the performance of the workload that I'd been testing.
> IOW, I wasn't able to discern a network performance difference between
> the baseline and those changes.
That is a bit unexpected that the performance wasn't worse with the patch Will
sent because it should have disabled the range invalidates since they these
invalidates will be getting rid of blocks? Which Graviton were you testing
this on?
Ali
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-04-04 21:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-28 19:04 [RFC] KVM: arm64: improving IO performance during unmap? Krister Johansen
2024-03-28 19:05 ` [PATCH] KVM: arm64: Limit stage2_apply_range() batch size to smallest block Krister Johansen
2024-03-29 13:48 ` Oliver Upton
2024-03-29 19:15 ` Krister Johansen
2024-03-30 10:17 ` Marc Zyngier
2024-04-02 17:00 ` Krister Johansen
2024-04-04 4:40 ` Krister Johansen
2024-04-04 21:27 ` Ali Saidi [this message]
2024-04-04 21:41 ` Krister Johansen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240404212742.11248-1-alisaidi@amazon.com \
--to=alisaidi@amazon.com \
--cc=catalin.marinas@arm.com \
--cc=james.morse@arm.com \
--cc=kjlx@templeofstupid.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=me@davidreaver.com \
--cc=oliver.upton@linux.dev \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).