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Date:   Thu, 30 May 2019 10:00:11 +0900
From:   Minchan Kim <minchan@kernel.org>
To:     Hillf Danton <hdanton@sina.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, Michal Hocko <mhocko@suse.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Tim Murray <timmurray@google.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Daniel Colascione <dancol@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        Sonny Rao <sonnyrao@google.com>,
        Brian Geffon <bgeffon@google.com>
Subject: Re: [RFC 7/7] mm: madvise support MADV_ANONYMOUS_FILTER and
 MADV_FILE_FILTER
Message-ID: <20190530010011.GD229459@google.com>
References: <20190520035254.57579-1-minchan@kernel.org>
 <20190520035254.57579-8-minchan@kernel.org>
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On Wed, May 29, 2019 at 12:36:04PM +0800, Hillf Danton wrote:
> 
> On Mon, 20 May 2019 12:52:54 +0900 Minchan Kim wrote:
> > 
> > With that, user could call a process_madvise syscall simply with a entire
> > range(0x0 - 0xFFFFFFFFFFFFFFFF) but either of MADV_ANONYMOUS_FILTER and
> > MADV_FILE_FILTER so there is no need to call the syscall range by range.
> > 
> Cool.
> 
> Look forward to seeing the non-RFC delivery.

I will drop this filter patch if userspace can parse address range fast.
Daniel suggested a new interface which could get necessary information
from the process with binary format so will it will remove endoce/decode
overhead as well as overhead we don't need to get like directory look
up.

Yes, with this filter option, it's best performance for a specific
usecase but sometime we need to give up *best* thing for *general*
stuff. I belive it's one of the category. ;-)