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Subject: Re: [PATCH RFC] virtio_balloon: conservative balloon page shrinking
To:     "Wang, Wei W" <wei.w.wang@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "virtualization@lists.linux-foundation.org" 
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        "alexander.h.duyck@linux.intel.com" 
        <alexander.h.duyck@linux.intel.com>,
        "rientjes@google.com" <rientjes@google.com>,
        "mhocko@kernel.org" <mhocko@kernel.org>,
        "namit@vmware.com" <namit@vmware.com>,
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References: <1580976107-16013-1-git-send-email-wei.w.wang@intel.com>
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From:   David Hildenbrand <david@redhat.com>
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Message-ID: <1f350e9f-e19d-8ef7-b63c-86bb4f52acc5@redhat.com>
Date:   Thu, 6 Feb 2020 10:49:22 +0100
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On 06.02.20 10:44, Wang, Wei W wrote:
> On Thursday, February 6, 2020 5:32 PM, David Hildenbrand wrote:
>>
>> If the page cache is empty, a drop_slab() will deflate the whole balloon if I
>> am not wrong.
>>
>> Especially, a echo 3 > /proc/sys/vm/drop_caches
>>
>> will first drop the page cache and then drop_slab()
> 
> Then that's the problem of "echo 3 > /proc/sys/vm/drop_cache" itself. It invokes other shrinkers as well (if considered an issue), need to be tweaked in the mm.

In short, I don't like this approach as long as a drop_slab() can
deflate the whole balloon and don't think this is the right approach then.


-- 
Thanks,

David / dhildenb