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Date:      Wed, 30 Jan 2013 22:58:31 +0200
From:      Andriy Gapon <avg@FreeBSD.org>
Cc:        freebsd-arch@FreeBSD.org
Subject:   axe vm.max_wired [Was: Allow small amount of memory be mlock()'ed by unprivileged process?]
Message-ID:  <51098977.4000603@FreeBSD.org>
In-Reply-To: <4FC9F94B.8060708@FreeBSD.org>
References:  <4FAC3EAB.6050303@delphij.net> <861umkurt8.fsf@ds4.des.no> <CAJ-VmokY%2Bpgcq999NHShbq-3rK3=oeWT2WY7NmTvVdXOHZJhdg@mail.gmail.com> <CAF6rxgmDW21aPJ5Mp6Tbk1z02ivw4UPhSaNEX%2BWiu7O0v13skA@mail.gmail.com> <20120517055425.GA802@infradead.org> <4FC762DD.90101@FreeBSD.org> <4FC81D9C.2080801@FreeBSD.org> <4FC8E29F.2010806@shatow.net> <4FC95A10.7000806@freebsd.org> <4FC9F94B.8060708@FreeBSD.org>

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on 02/06/2012 14:30 Andriy Gapon said the following:
> o  There is also vm.max_wired sysctl (with no equivalent tunable), which
> specifies number of _pages_ that can be wired system wide (by both kernel and
> userland).  But note that the limit applies only to userland requests, the
> kernel is allowed to wire new pages even when the limit is exceeded.  By default
> the limit is set to 1/3 of available pages.

I would like to propose to axe vm.max_wired limit.
It is not good when too many pages are wired, but...

This limit is quite arbitrary (why 1/3).
It's no good for ZFS systems where e.g. 90% of memory can be normally wired by
ZFS in kernel.

So this limit should be either axed or perhaps replaced with some much higher
limit like e.g. v_page_count - 2 * v_free_target or some such number "close" to
v_page_count.

-- 
Andriy Gapon



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