From: Alexander Duyck <alexander.duyck@gmail.com> To: mhocko@kernel.org Cc: pavel.tatashin@microsoft.com, linux-nvdimm@lists.01.org, Dave Hansen <dave.hansen@intel.com>, LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, jglisse@redhat.com, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@kernel.org> Subject: Re: [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning Date: Wed, 12 Sep 2018 07:49:06 -0700 [thread overview] Message-ID: <CAKgT0UdvhV7U5Zniq=KskXz2QsRP8C7ctr5=ZtJwYAVpBT-RHw@mail.gmail.com> (raw) In-Reply-To: <20180912141053.GL10951@dhcp22.suse.cz> On Wed, Sep 12, 2018 at 7:10 AM Michal Hocko <mhocko@kernel.org> wrote: > > On Mon 10-09-18 16:43:41, Alexander Duyck wrote: > > From: Alexander Duyck <alexander.h.duyck@intel.com> > > > > On systems with a large amount of memory it can take a significant amount > > of time to initialize all of the page structs with the PAGE_POISON_PATTERN > > value. I have seen it take over 2 minutes to initialize a system with > > over 12GB of RAM. > > > > In order to work around the issue I had to disable CONFIG_DEBUG_VM and then > > the boot time returned to something much more reasonable as the > > arch_add_memory call completed in milliseconds versus seconds. However in > > doing that I had to disable all of the other VM debugging on the system. > > > > In order to work around a kernel that might have CONFIG_DEBUG_VM enabled on > > a system that has a large amount of memory I have added a new kernel > > parameter named "page_init_poison" that can be set to "off" in order to > > disable it. > > I am still not convinced that this all is worth the additional code. It > is much better than a new config option for sure. If we really want this > though then I suggest that the parameter handler should note the > disabled state (when CONFIG_DEBUG_VM is on) to the kernel log. I would > also make it explicit who might want to do that in the parameter > description. Anything specific in terms of the kernel log message we are looking for? I'll probably just go with "Page struct poisoning disabled by kernel command line option 'page_init_poison'" or something along those lines. > > + page_init_poison= [KNL] Boot-time parameter changing the > > + state of poisoning of page structures during early > > + boot. Used to verify page metadata is not accessed > > + prior to initialization. Available with > > + CONFIG_DEBUG_VM=y. > > + off: turn off poisoning > > + on: turn on poisoning (default) > > + > > what about the following wording or something along those lines > > Boot-time parameter to control struct page poisoning which is a > debugging feature to catch unitialized struct page access. This option > is available only for CONFIG_DEBUG_VM=y and it affects boot time > (especially on large systems). If there are no poisoning bugs reported > on the particular system and workload it should be safe to disable it to > speed up the boot time. That works for me. I will update it for the next release. Thanks. - Alex _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
next prev parent reply other threads:[~2018-09-12 14:49 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-09-10 23:43 [PATCH 0/4] Address issues slowing persistent memory initialization Alexander Duyck 2018-09-10 23:43 ` [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck 2018-09-11 0:35 ` Alexander Duyck 2018-09-11 16:50 ` Dan Williams 2018-09-11 20:01 ` Alexander Duyck 2018-09-11 20:24 ` Dan Williams 2018-09-12 13:24 ` Pasha Tatashin 2018-09-12 14:10 ` Michal Hocko 2018-09-12 14:49 ` Alexander Duyck [this message] 2018-09-12 15:23 ` Dave Hansen 2018-09-12 16:36 ` Alexander Duyck 2018-09-12 16:43 ` Dave Hansen 2018-09-10 23:43 ` [PATCH 2/4] mm: Create non-atomic version of SetPageReserved for init use Alexander Duyck 2018-09-12 13:28 ` Pasha Tatashin 2018-09-10 23:43 ` [PATCH 3/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck 2018-09-11 7:49 ` kbuild test robot 2018-09-11 7:54 ` kbuild test robot 2018-09-11 22:35 ` Dan Williams 2018-09-12 0:51 ` Alexander Duyck 2018-09-12 0:59 ` Dan Williams 2018-09-12 13:59 ` Pasha Tatashin 2018-09-12 15:48 ` Alexander Duyck 2018-09-12 15:54 ` Pasha Tatashin 2018-09-12 16:44 ` Alexander Duyck 2018-09-12 16:50 ` Dan Williams 2018-09-12 17:46 ` Pasha Tatashin 2018-09-12 19:11 ` Dan Williams 2018-09-10 23:44 ` [PATCH 4/4] nvdimm: Trigger the device probe on a cpu local to the device Alexander Duyck 2018-09-11 0:37 ` Alexander Duyck 2018-09-12 5:48 ` Dan Williams 2018-09-12 13:44 ` Pasha Tatashin
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