From: Christoph Lameter <cl@linux.com> To: Hugh Dickins <hughd@google.com> Cc: Michael Ellerman <mpe@ellerman.id.au>, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Subject: Re: 4.12-rc ppc64 4k-page needs costly allocations Date: Thu, 1 Jun 2017 13:16:08 -0500 (CDT) [thread overview] Message-ID: <alpine.DEB.2.20.1706011306560.11993@east.gentwo.org> (raw) In-Reply-To: <alpine.LSU.2.11.1706011002130.3014@eggly.anvils> On Thu, 1 Jun 2017, Hugh Dickins wrote: > CONFIG_SLUB_DEBUG_ON=y. My SLAB|SLUB config options are > > CONFIG_SLUB_DEBUG=y > # CONFIG_SLUB_MEMCG_SYSFS_ON is not set > # CONFIG_SLAB is not set > CONFIG_SLUB=y > # CONFIG_SLAB_FREELIST_RANDOM is not set > CONFIG_SLUB_CPU_PARTIAL=y > CONFIG_SLABINFO=y > # CONFIG_SLUB_DEBUG_ON is not set > CONFIG_SLUB_STATS=y Thats fine. > But I think you are now surprised, when I say no slub_debug options > were on. Here's the output from /sys/kernel/slab/pgtable-2^12/* > (before I tried the new kernel with Aneesh's fix patch) > in case they tell you anything... > > pgtable-2^12/poison:0 > pgtable-2^12/red_zone:0 > pgtable-2^12/reserved:0 > pgtable-2^12/sanity_checks:0 > pgtable-2^12/store_user:0 Ok so debugging was off but the slab cache has a ctor callback which mandates that the free pointer cannot use the free object space when the object is not in use. Thus the size of the object must be increased to accomodate the freepointer. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
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From: Christoph Lameter <cl@linux.com> To: Hugh Dickins <hughd@google.com> Cc: Michael Ellerman <mpe@ellerman.id.au>, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Subject: Re: 4.12-rc ppc64 4k-page needs costly allocations Date: Thu, 1 Jun 2017 13:16:08 -0500 (CDT) [thread overview] Message-ID: <alpine.DEB.2.20.1706011306560.11993@east.gentwo.org> (raw) In-Reply-To: <alpine.LSU.2.11.1706011002130.3014@eggly.anvils> On Thu, 1 Jun 2017, Hugh Dickins wrote: > CONFIG_SLUB_DEBUG_ON=y. My SLAB|SLUB config options are > > CONFIG_SLUB_DEBUG=y > # CONFIG_SLUB_MEMCG_SYSFS_ON is not set > # CONFIG_SLAB is not set > CONFIG_SLUB=y > # CONFIG_SLAB_FREELIST_RANDOM is not set > CONFIG_SLUB_CPU_PARTIAL=y > CONFIG_SLABINFO=y > # CONFIG_SLUB_DEBUG_ON is not set > CONFIG_SLUB_STATS=y Thats fine. > But I think you are now surprised, when I say no slub_debug options > were on. Here's the output from /sys/kernel/slab/pgtable-2^12/* > (before I tried the new kernel with Aneesh's fix patch) > in case they tell you anything... > > pgtable-2^12/poison:0 > pgtable-2^12/red_zone:0 > pgtable-2^12/reserved:0 > pgtable-2^12/sanity_checks:0 > pgtable-2^12/store_user:0 Ok so debugging was off but the slab cache has a ctor callback which mandates that the free pointer cannot use the free object space when the object is not in use. Thus the size of the object must be increased to accomodate the freepointer.
next prev parent reply other threads:[~2017-06-01 18:16 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-05-30 19:43 4.12-rc ppc64 4k-page needs costly allocations Hugh Dickins 2017-05-30 19:43 ` Hugh Dickins 2017-05-31 6:46 ` Michael Ellerman 2017-05-31 6:46 ` Michael Ellerman 2017-05-31 14:09 ` Christoph Lameter 2017-05-31 14:09 ` Christoph Lameter 2017-05-31 18:44 ` Hugh Dickins 2017-05-31 18:44 ` Hugh Dickins 2017-05-31 19:02 ` Mathieu Malaterre 2017-05-31 19:02 ` Mathieu Malaterre 2017-06-01 15:31 ` Christoph Lameter 2017-06-01 15:31 ` Christoph Lameter 2017-06-01 17:22 ` Hugh Dickins 2017-06-01 17:22 ` Hugh Dickins 2017-06-01 18:16 ` Christoph Lameter [this message] 2017-06-01 18:16 ` Christoph Lameter 2017-06-01 18:37 ` Hugh Dickins 2017-06-01 18:37 ` Hugh Dickins 2017-06-02 3:09 ` Michael Ellerman 2017-06-02 3:09 ` Michael Ellerman 2017-06-02 4:00 ` Hugh Dickins 2017-06-02 4:00 ` Hugh Dickins 2017-06-02 14:33 ` Christoph Lameter 2017-06-02 14:33 ` Christoph Lameter 2017-06-08 5:44 ` Michael Ellerman 2017-06-08 5:44 ` Michael Ellerman 2017-06-02 14:32 ` Christoph Lameter 2017-06-02 14:32 ` Christoph Lameter 2017-06-08 5:52 ` Michael Ellerman 2017-06-08 5:52 ` Michael Ellerman 2017-05-31 14:06 ` Christoph Lameter 2017-05-31 14:06 ` Christoph Lameter 2017-06-01 4:19 ` Aneesh Kumar K.V 2017-06-01 4:19 ` Aneesh Kumar K.V 2017-06-01 16:57 ` Hugh Dickins 2017-06-01 16:57 ` Hugh Dickins
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