linux-kernel - Re: [PATCH] jffs2: implement mount option to configure endianness

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Date:   Thu, 8 Nov 2018 07:25:30 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
Cc:     "danielwa@...co.com" <danielwa@...co.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "nkela@...co.com" <nkela@...co.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "xe-linux-external@...co.com" <xe-linux-external@...co.com>
Subject: Re: [PATCH] jffs2: implement mount option to configure endianness

On Wed, Nov 07, 2018 at 06:41:47PM +0000, Joakim Tjernlund wrote:
> > Certainly not. I'm not sure which architectures do have Spectre V2
> > mitigations which make indirect branches expensive now... perhaps there is
> > no intersection with the cases where we really care about JFFS2 being
> > CPU-bound?
> 
> All that passing of a new extra arg and extra if .. elif .. does cost too.

I know of no current microarchitecture where an indirect call is cheaper
than a simple branch, which can be very well predicted.