linux-kernel - Re: [PATCH 1/2] xen: enter/exit lazy_mmu_mode around m2p

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.00.1203271737280.15151@kaball-desktop>
Date:	Tue, 27 Mar 2012 17:56:16 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [PATCH 1/2] xen: enter/exit lazy_mmu_mode around m2p_override
 calls

On Tue, 27 Mar 2012, Konrad Rzeszutek Wilk wrote:
> On Tue, Mar 27, 2012 at 02:52:43PM +0100, Stefano Stabellini wrote:
> > This patch is a significant performance improvement for the
> 
> How much? 10%? 90%?

I think you are overestimating the meaning of "significant" :)

It is about 6% using grant_table and 2% using blkback.


> > m2p_override.
> 
> Can you explain what those calls do in the git commit description please?

Right, I have been way too concise.

Each m2p_add/remove_override call issues a MULTI_grant_table_op and a
__flush_tlb_single if kmap_op != NULL.
Batching all the calls together is a great performance benefit because
it means issuing one hypercall total rather than two hypercall per page.

I'll resend with a proper commit message.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/