From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Eric B Munson <emunson@akamai.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>, Vlastimil Babka <vbabka@suse.cz>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Chris Metcalf <cmetcalf@ezchip.com>,
Guenter Roeck <linux@roeck-us.net>,
linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mips@linux-mips.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
linux-xtensa@linux-xtensa.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH V5 5/7] mm: mmap: Add mmap flag to request VM_LOCKONFAULT
Date: Mon, 27 Jul 2015 10:31:29 +0300 [thread overview]
Message-ID: <20150727073129.GE11657@node.dhcp.inet.fi> (raw)
In-Reply-To: <1437773325-8623-6-git-send-email-emunson@akamai.com>
On Fri, Jul 24, 2015 at 05:28:43PM -0400, Eric B Munson wrote:
> The cost of faulting in all memory to be locked can be very high when
> working with large mappings. If only portions of the mapping will be
> used this can incur a high penalty for locking.
>
> Now that we have the new VMA flag for the locked but not present state,
> expose it as an mmap option like MAP_LOCKED -> VM_LOCKED.
As I mentioned before, I don't think this interface is justified.
MAP_LOCKED has known issues[1]. The MAP_LOCKED problem is not necessary
affects MAP_LOCKONFAULT, but still.
Let's not add new interface unless it's demonstrably useful.
[1] http://lkml.kernel.org/g/20150114095019.GC4706@dhcp22.suse.cz
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2015-07-27 7:31 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-24 21:28 [PATCH V5 0/7] Allow user to request memory to be locked on page fault Eric B Munson
2015-07-24 21:28 ` [PATCH V5 1/7] mm: mlock: Refactor mlock, munlock, and munlockall code Eric B Munson
2015-07-27 6:31 ` Kirill A. Shutemov
2015-07-24 21:28 ` [PATCH V5 2/7] mm: mlock: Add new mlock system call Eric B Munson
2015-07-27 6:43 ` Kirill A. Shutemov
2015-07-24 21:28 ` [PATCH V5 3/7] mm: Introduce VM_LOCKONFAULT Eric B Munson
2015-07-27 7:02 ` Kirill A. Shutemov
2015-07-24 21:28 ` [PATCH V5 4/7] mm: mlock: Add mlock flags to enable VM_LOCKONFAULT usage Eric B Munson
2015-07-27 7:15 ` Kirill A. Shutemov
2015-07-24 21:28 ` [PATCH V5 5/7] mm: mmap: Add mmap flag to request VM_LOCKONFAULT Eric B Munson
2015-07-27 7:31 ` Kirill A. Shutemov [this message]
2015-07-27 13:41 ` Eric B Munson
2015-07-27 14:03 ` Kirill A. Shutemov
2015-07-27 14:11 ` Eric B Munson
2015-07-24 21:28 ` [PATCH V5 6/7] selftests: vm: Add tests for lock on fault Eric B Munson
2015-07-24 21:28 ` [PATCH V5 7/7] mips: Add entry for new mlock2 syscall Eric B Munson
2015-07-27 9:08 ` [PATCH V5 0/7] Allow user to request memory to be locked on page fault Vlastimil Babka
2015-07-27 13:35 ` Eric B Munson
2015-07-27 14:16 ` Vlastimil Babka
2015-07-27 14:54 ` Eric B Munson
2015-07-27 15:40 ` Vlastimil Babka
2015-07-28 11:17 ` Michal Hocko
2015-07-28 11:23 ` Vlastimil Babka
2015-07-28 13:49 ` Eric B Munson
2015-07-28 15:10 ` Vlastimil Babka
2015-07-28 18:06 ` Eric B Munson
2015-07-29 10:45 ` Michal Hocko
2015-07-29 10:49 ` Vlastimil Babka
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