linux-kernel - Re: [PATCH RFC 0/6] mm/kdump: allow to exclude pages that are logically offline

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Message-ID: <B6456717-0A6F-4957-A7F2-11599701226A@vmware.com>
Date:   Thu, 15 Nov 2018 01:42:30 +0000
From:   Julien Freche <jfreche@...are.com>
To:     Nadav Amit <namit@...are.com>,
        David Hildenbrand <david@...hat.com>,
        linux-mm <linux-mm@...ck.org>
CC:     LKML <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>, Baoquan He <bhe@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Christian Hansen <chansen3@...co.com>,
        Dave Young <dyoung@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Jonathan Corbet <corbet@....net>,
        Juergen Gross <jgross@...e.com>,
        Kairui Song <kasong@...hat.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Len Brown <len.brown@...el.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Miles Chen <miles.chen@...iatek.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Omar Sandoval <osandov@...com>, Pavel Machek <pavel@....cz>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH RFC 0/6] mm/kdump: allow to exclude pages that are
 logically offline

>On 11/14/18, 3:41 PM, "Nadav Amit" <namit@...are.com> wrote:
>>From: David Hildenbrand
>>Sent: November 14, 2018 at 11:05:38 PM GMT
>> Subject: Re: [PATCH RFC 0/6] mm/kdump: allow to exclude pages that are logically offline
>> 
>> 
>> Can you share if something like this is also desired for vmware's
>> implementation? (I tagged this as RFC to get some more feedback)
>> 
>> It should in theory be as simple as adding a handful of
>> _SetPageOffline()/_ClearPageOffline() at the right spots.
>    
> Thanks, I was just suspecting it is personal ;-)
>
> I would obviously prefer that your changes would be done on top of those
> that were skipped. This patch-set sounds very reasonable to me, but I prefer
> that Julien (cc’d) would also give his opinion.
    
I think this is desirable for VMware's implementation also. You are right,
dumping data that is not relevant is a waste :-) 
I haven't heard of any panic/issue due to this but that's still a good optimization.

Nadav or I could help to test that on ESX if required.

Regards,

-- 
Julien Freche