From: Ingo Molnar <mingo@kernel.org>
To: Matteo Rizzo <matteorizzo@google.com>
Cc: "Lameter, Christopher" <cl@os.amperecomputing.com>,
Dave Hansen <dave.hansen@intel.com>,
penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com,
akpm@linux-foundation.org, vbabka@suse.cz,
roman.gushchin@linux.dev, 42.hyeyoo@gmail.com,
keescook@chromium.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
linux-hardening@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com, corbet@lwn.net, luto@kernel.org,
peterz@infradead.org, jannh@google.com, evn@google.com,
poprdi@google.com, jordyzomer@google.com,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator
Date: Mon, 18 Sep 2023 19:39:43 +0200 [thread overview]
Message-ID: <ZQiLX0W2Tcr+wdJT@gmail.com> (raw)
In-Reply-To: <CAHKB1w+rVyww0UrHhzeGfPA7FM482Z-7ApzXvekVqLHvTDAV3Q@mail.gmail.com>
* Matteo Rizzo <matteorizzo@google.com> wrote:
> On Fri, 15 Sept 2023 at 18:30, Lameter, Christopher
> <cl@os.amperecomputing.com> wrote:
> >
> > On Fri, 15 Sep 2023, Dave Hansen wrote:
> >
> > > What's the cost?
> >
> > The only thing that I see is 1-2% on kernel compilations (and "more on
> > machines with lots of cores")?
>
> I used kernel compilation time (wall clock time) as a benchmark while
> preparing the series. Lower is better.
>
> Intel Skylake, 112 cores:
>
> LABEL | COUNT | MIN | MAX | MEAN | MEDIAN | STDDEV
> ---------------+-------+---------+---------+---------+---------+--------
> SLAB_VIRTUAL=n | 150 | 49.700s | 51.320s | 50.449s | 50.430s | 0.29959
> SLAB_VIRTUAL=y | 150 | 50.020s | 51.660s | 50.880s | 50.880s | 0.30495
> | | +0.64% | +0.66% | +0.85% | +0.89% | +1.79%
>
> AMD Milan, 256 cores:
>
> LABEL | COUNT | MIN | MAX | MEAN | MEDIAN | STDDEV
> ---------------+-------+---------+---------+---------+---------+--------
> SLAB_VIRTUAL=n | 150 | 25.480s | 26.550s | 26.065s | 26.055s | 0.23495
> SLAB_VIRTUAL=y | 150 | 25.820s | 27.080s | 26.531s | 26.540s | 0.25974
> | | +1.33% | +2.00% | +1.79% | +1.86% | +10.55%
That's sadly a rather substantial overhead for a compiler/linker workload
that is dominantly user-space: a kernel build is about 90% user-time and
10% system-time:
$ perf stat --null make -j64 vmlinux
...
Performance counter stats for 'make -j64 vmlinux':
59.840704481 seconds time elapsed
2000.774537000 seconds user
219.138280000 seconds sys
What's the split of the increase in overhead due to SLAB_VIRTUAL=y, between
user-space execution and kernel-space execution?
Thanks,
Ingo
next prev parent reply other threads:[~2023-09-18 17:39 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-15 10:59 [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 01/14] mm/slub: don't try to dereference invalid freepointers Matteo Rizzo
2023-09-15 20:50 ` Kees Cook
2023-09-30 11:04 ` Hyeonggon Yoo
2023-09-15 10:59 ` [RFC PATCH 02/14] mm/slub: add is_slab_addr/is_slab_page helpers Matteo Rizzo
2023-09-15 20:55 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 03/14] mm/slub: move kmem_cache_order_objects to slab.h Matteo Rizzo
2023-09-15 20:56 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 04/14] mm: use virt_to_slab instead of folio_slab Matteo Rizzo
2023-09-15 20:59 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 05/14] mm/slub: create folio_set/clear_slab helpers Matteo Rizzo
2023-09-15 21:02 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 06/14] mm/slub: pass additional args to alloc_slab_page Matteo Rizzo
2023-09-15 21:03 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 07/14] mm/slub: pass slab pointer to the freeptr decode helper Matteo Rizzo
2023-09-15 21:06 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 08/14] security: introduce CONFIG_SLAB_VIRTUAL Matteo Rizzo
2023-09-15 21:07 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 09/14] mm/slub: add the slab freelists to kmem_cache Matteo Rizzo
2023-09-15 21:08 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 10/14] x86: Create virtual memory region for SLUB Matteo Rizzo
2023-09-15 21:13 ` Kees Cook
2023-09-15 21:49 ` Dave Hansen
2023-09-18 8:54 ` Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 11/14] mm/slub: allocate slabs from virtual memory Matteo Rizzo
2023-09-15 21:22 ` Kees Cook
2023-09-15 21:57 ` Dave Hansen
2023-10-11 9:17 ` Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 12/14] mm/slub: introduce the deallocated_pages sysfs attribute Matteo Rizzo
2023-09-15 21:23 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 13/14] mm/slub: sanity-check freepointers Matteo Rizzo
2023-09-15 21:26 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 14/14] security: add documentation for SLAB_VIRTUAL Matteo Rizzo
2023-09-15 21:34 ` Kees Cook
2023-09-20 9:04 ` Vlastimil Babka
2023-09-15 15:19 ` [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator Dave Hansen
2023-09-15 16:30 ` Lameter, Christopher
2023-09-18 12:08 ` Matteo Rizzo
2023-09-18 17:39 ` Ingo Molnar [this message]
2023-09-18 18:05 ` Linus Torvalds
2023-09-19 15:48 ` Matteo Rizzo
2023-09-19 16:02 ` Dave Hansen
2023-09-19 17:56 ` Kees Cook
2023-09-19 18:49 ` Linus Torvalds
2023-09-19 13:42 ` Matteo Rizzo
2023-09-19 15:56 ` Dave Hansen
2023-09-20 7:44 ` Ingo Molnar
2023-09-20 8:49 ` Vlastimil Babka
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