linux-kernel - Re: [PATCH v2 0/1] Accept unaccepted kexec segments' destination addresses

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Message-ID: <CAMGD6P3r-S-Va-TRvVjZ808on9+-wFJ_VeTpQ+FEN1jBbhmnXw@mail.gmail.com>
Date: Wed, 19 Feb 2025 15:03:30 -0800
From: Jianxiong Gao <jxgao@...gle.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...el.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, 
	Baoquan He <bhe@...hat.com>, "Kirill A. Shutemov" <kirill@...temov.name>, akpm@...ux-foundation.org, 
	kexec@...ts.infradead.org, Yan Zhao <yan.y.zhao@...el.com>, 
	linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, x86@...nel.org, 
	rick.p.edgecombe@...el.com, security@...nel.org
Subject: Re: [PATCH v2 0/1] Accept unaccepted kexec segments' destination addresses

> > It sounds like you're advocating for the "slow guest boot" option.
> > Kirill, can you remind us how fast a guest boots to the shell for
> > modestly-sized (say 256GB) memory with "accept_memory=eager" versus
> > "accept_memory=lazy"? IIRC, it was a pretty remarkable difference.
>
> I only have 128GB machine readily available and posted some number on
> other thread[1]:
>
>   On single vCPU it takes about a minute to accept 90GiB of memory.
>
>   It improves a bit with number of vCPUs. It is 40 seconds with 4 vCPU, but
>   it doesn't scale past that in my setup.
>
We have seen similar boot performance improvements on our larger shapes
of VMs. Both lazy accept and kexec with TDX are important features for us.


--
Jianxiong Gao