From: David Woodhouse <dwmw2@infradead.org>
To: Usama Arif <usama.arif@bytedance.com>, tglx@linutronix.de
Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
paulmck@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
hewenliang4@huawei.com, thomas.lendacky@amd.com,
seanjc@google.com, pmenzel@molgen.mpg.de,
fam.zheng@bytedance.com, punit.agrawal@bytedance.com,
simon.evans@bytedance.com, liangma@liangbit.com
Subject: Re: [PATCH 0/9] Parallel CPU bringup for x86_64
Date: Thu, 02 Feb 2023 10:02:13 +0000 [thread overview]
Message-ID: <de9c33a14c370d09cefaa331b18525e164436082.camel@infradead.org> (raw)
In-Reply-To: <20230201204338.1337562-1-usama.arif@bytedance.com>
[-- Attachment #1: Type: text/plain, Size: 2366 bytes --]
On Wed, 2023-02-01 at 20:43 +0000, Usama Arif wrote:
> This patchseries is from the work done by David Woodhouse (v4: https://lore.kernel.org/all/20220201205328.123066-1-dwmw2@infradead.org/).
> The parallel CPU bringup is disabled for all AMD CPUs in this version: (see discussions: https://lore.kernel.org/all/bc3f2b1332c4bb77558df8aa36493a55542fe5b9.camel@infradead.org/ and
> https://lore.kernel.org/all/3b6ac86fdc800cac5806433daf14a9095be101e9.camel@infradead.org/).
>
> Doing INIT/SIPI/SIPI in parallel brings down the time for smpboot from ~700ms
> to 100ms (85% improvement) on a server with 128 CPUs split across 2 NUMA
> nodes.
>
> Adding another cpuhp state for do_wait_cpu_initialized to make sure cpu_init
> is reached in parallel as proposed by David in v1 will bring it down further
> to ~30ms. Making this change would be dependent on this patchseries, so they
> could be explored if this gets merged.
>
> Changes across versions:
> v2: Cut it back to just INIT/SIPI/SIPI in parallel for now, nothing more
> v3: Clean up x2apic patch, add MTRR optimisation, lock topology update
> in preparation for more parallelisation.
> v4: Fixes to the real mode parallelisation patch spotted by SeanC, to
> avoid scribbling on initial_gs in common_cpu_up(), and to allow all
> 24 bits of the physical X2APIC ID to be used. That patch still needs
> a Signed-off-by from its original author, who once claimed not to
> remember writing it at all. But now we've fixed it, hopefully he'll
> admit it now :)
> v5: rebase to v6.1 and remeasure performance, disable parallel bringup
> for AMD CPUs.
Thanks, Usama.
I've updated to v6.2-rc6 since there were a few more tweaks required
(and we should double-check that the new handling of cache_ap_init from
a dedicated cpuhp step works right if that ends up being done in
parallel).
I also fixed up the complaints from the test robot; including
<linux/smpboot.h> from smpboot.c and making do_cpu_up() static, and
putting #ifdef CONFIG_SMP around the 'are we booting the AP?' check and
code segment in head_64.S.
I've made the AMD thing a CPU bug as Peter suggested, and pushed it to
https://git.infradead.org/users/dwmw2/linux.git/shortlog/refs/heads/parallel-6.2-rc6
for you to do the real work of actually testing it :)
[-- Attachment #2: smime.p7s --]
[-- Type: application/pkcs7-signature, Size: 5965 bytes --]
next prev parent reply other threads:[~2023-02-02 10:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 20:43 [PATCH 0/9] Parallel CPU bringup for x86_64 Usama Arif
2023-02-01 20:43 ` [PATCH 1/9] x86/apic/x2apic: Fix parallel handling of cluster_mask Usama Arif
2023-02-01 20:43 ` [PATCH 2/9] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-02-01 20:43 ` [PATCH 3/9] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-02-01 20:43 ` [PATCH 4/9] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-02-01 20:43 ` [PATCH 5/9] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-02-01 20:43 ` [PATCH 6/9] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-02-01 20:43 ` [PATCH 7/9] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-02-01 20:43 ` [PATCH 8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup Usama Arif
2023-02-01 20:43 ` [PATCH 9/9] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-02-02 10:02 ` David Woodhouse [this message]
2023-02-02 21:59 ` [PATCH 0/9] Parallel CPU bringup for x86_64 Usama Arif
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=de9c33a14c370d09cefaa331b18525e164436082.camel@infradead.org \
--to=dwmw2@infradead.org \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=fam.zheng@bytedance.com \
--cc=hewenliang4@huawei.com \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=liangma@liangbit.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mimoja@mimoja.de \
--cc=mingo@redhat.com \
--cc=paulmck@kernel.org \
--cc=pbonzini@redhat.com \
--cc=pmenzel@molgen.mpg.de \
--cc=punit.agrawal@bytedance.com \
--cc=rcu@vger.kernel.org \
--cc=seanjc@google.com \
--cc=simon.evans@bytedance.com \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=usama.arif@bytedance.com \
--cc=x86@kernel.org \
/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).