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Date:   Tue, 24 Oct 2023 13:30:04 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     "Luck, Tony" <tony.luck@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
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        "x86@kernel.org" <x86@kernel.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        "Lutomirski, Andy" <luto@kernel.org>,
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Subject: RE: [PATCH  v2 1/6] x86/bugs: Add asm helpers for executing VERW
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On October 24, 2023 12:40:02 PM PDT, "Luck, Tony" <tony=2Eluck@intel=2Ecom>=
 wrote:
>> Sure it could, but it would mean the kernel is sitting on an average of=
 6 MB of unusable memory=2E It would also mean that unloaded modules would =
create holes in that memory which would have to be managed=2E
>
>On my Fedora38 desktop:
>
>$ lsmod | awk '{ bytes +=3D $2 } END {print bytes/(1024*1024)}'
>21=2E0859
>
>Lots more than 6MB memory already essentially pinned by loaded modules=2E
>
>$ head -3 /proc/meminfo
>MemTotal:       65507344 kB
>MemFree:        56762336 kB
>MemAvailable:   63358552 kB
>
>Pinning 20 or so Mbytes isn't going to make a dent in that free memory=2E
>
>Managing the holes for unloading/reloading modules adds some complexity =
=2E=2E=2E but shouldn't be awful=2E
>
>If this code managed at finer granularity than "page", it would save some=
 memory=2E
>
>$ lsmod | wc -l
>123
>
>All those modules rounding text/data up to 4K boundaries is wasting a bun=
ch of it=2E
>
>-Tony
>
>
>

Sure, but is it worth the effort?