From: Paul Mackerras <paulus@ozlabs.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: benh@kernel.crashing.org, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH 0/7] Remove 4k subpage tracking with hash 64K config
Date: Thu, 29 Oct 2015 14:00:29 +1100 [thread overview]
Message-ID: <20151029030029.GA31681@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <1445371953-9627-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
On Wed, Oct 21, 2015 at 01:42:26AM +0530, Aneesh Kumar K.V wrote:
> Hi,
>
> This patch series is on top of the series posted at
>
> https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135299.html
> "[PATCH V4 00/31] powerpc/mm: Update page table format for book3s 64". In this
> series we remove 4k subpage tracking with 64K config. Instead we do a hash
> table lookup to get the slot information of 4k hash ptes. This also allow us
> to remove real_pte_t. Side effect of the change is that a specific 4k slot
> lookup can result in multiple H_READ hcalls. But that should only impact
> when we are using 4K subpages which should be rare.
>
> NOTE: I only tested this on systemsim. Wanted to get this out to get early
> feedback.
I tried this on a quad G5 and it seems to work just fine. On a kernel
compile test there was very little difference in speed - I measured
about 0.4% slowdown but that may not be statistically significant.
This was with 64k pages configured and THP enabled.
Paul.
next prev parent reply other threads:[~2015-10-29 3:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-20 20:12 [RFC PATCH 0/7] Remove 4k subpage tracking with hash 64K config Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 1/7] powerpc/mm: Don't hardcode page table size Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 2/7] powerpc/mm: Don't hardcode the hash pte slot shift Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 3/7] powerpc/nohash: Update 64K nohash config to have 32 pte fragement Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 4/7] powerpc/mm: Don't track 4k subpage information with 64k linux page size Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 5/7] powerpc/mm: update frag size Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 6/7] powerpc/mm: Update pte_iterate_hashed_subpaes args Aneesh Kumar K.V
2015-10-20 20:12 ` [RFC PATCH 7/7] powerpc/mm: getrid of real_pte_t Aneesh Kumar K.V
2015-10-29 3:00 ` Paul Mackerras [this message]
2015-11-03 5:08 ` [RFC PATCH 0/7] Remove 4k subpage tracking with hash 64K config Aneesh Kumar K.V
2015-11-03 5:30 ` Benjamin Herrenschmidt
2015-11-03 9:18 ` Michael Ellerman
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