linux-kernel - Re: [PATCH] x86/mm: Tracking linear mapping split events since boot

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Message-ID: <YA8q3eSTuIrUmPeM@slm.duckdns.org>
Date:   Mon, 25 Jan 2021 15:32:29 -0500
From:   Tejun Heo <tj@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Saravanan D <saravanand@...look.com>, x86@...nel.org,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH] x86/mm: Tracking linear mapping split events since boot

Hello,

On Mon, Jan 25, 2021 at 12:15:51PM -0800, Dave Hansen wrote:
> > DirectMap4k:     3505112 kB
> > DirectMap2M:    19464192 kB
> > DirectMap1G:    12582912 kB
> > DirectMap2MSplits:  1705
> > DirectMap1GSplits:    20
> 
> This seems much more like something we'd want in /proc/vmstat or as a
> tracepoint than meminfo.  A tracepoint would be especially nice because
> the trace buffer could actually be examined if an admin finds an
> excessive number of these.

Adding a TP sure can be helpful but I'm not sure how that'd make counters
unnecessary given that the accumulated number of events since boot is what
matters.

Thanks.

-- 
tejun