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From: Luis Chamberlain <mcgrof@kernel.org>
To: Song Liu <song@kernel.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	linux-mm@kvack.org, ast@kernel.org, daniel@iogearbox.net,
	peterz@infradead.org, torvalds@linux-foundation.org,
	kernel-team@fb.com
Subject: Re: [PATCH v3 bpf-next 5/8] bpf: use module_alloc_huge for bpf_prog_pack
Date: Fri, 20 May 2022 18:20:55 -0700	[thread overview]
Message-ID: <Yog+d+oR5TtPp2cs@bombadil.infradead.org> (raw)
In-Reply-To: <Yog5yXqAQZAmpgCD@bombadil.infradead.org>

On Fri, May 20, 2022 at 06:00:57PM -0700, Luis Chamberlain wrote:
> On Thu, May 19, 2022 at 08:15:45PM -0700, Song Liu wrote:
> > Use module_alloc_huge for bpf_prog_pack so that BPF programs sit on
> > PMD_SIZE pages. This benefits system performance by reducing iTLB miss
> > rate. Benchmark of a real web service workload shows this change gives
> > another ~0.2% performance boost on top of PAGE_SIZE bpf_prog_pack
> > (which improve system throughput by ~0.5%).

Also, seems like a is a missed opportunity to show iTLB misses with more
detail. If there was a selftest to stress bpf JIT you could use perf and
enable anyone to quanitfy gains. Dave hinted with some ideas with perf:

perf stat -e cpu/event=0x8,umask=0x84,name=dtlb_load_misses_walk_duration/,cpu/event=0x8,umask=0x82,name=dtlb_load_misses_walk_completed/,cpu/event=0x49,umask=0x4,name=dtlb_store_misses_walk_duration/,cpu/event=0x49,umask=0x2,name=dtlb_store_misses_walk_completed/,cpu/event=0x85,umask=0x4,name=itlb_misses_walk_duration/,cpu/event=0x85,umask=0x2,name=itlb_misses_walk_completed/ some_bpf_jit_test

  Luis

  reply	other threads:[~2022-05-21  1:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20  3:15 [PATCH v3 bpf-next 0/8] bpf_prog_pack followup Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 1/8] bpf: fill new bpf_prog_pack with illegal instructions Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 2/8] x86/alternative: introduce text_poke_set Song Liu
2022-05-22  5:38   ` Hyeonggon Yoo
2022-05-20  3:15 ` [PATCH v3 bpf-next 3/8] bpf: introduce bpf_arch_text_invalidate for bpf_prog_pack Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 4/8] module: introduce module_alloc_huge Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 5/8] bpf: use module_alloc_huge for bpf_prog_pack Song Liu
2022-05-21  1:00   ` Luis Chamberlain
2022-05-21  1:20     ` Luis Chamberlain [this message]
2022-05-21  3:20     ` Edgecombe, Rick P
2022-05-21 20:06       ` Luis Chamberlain
2022-05-24 17:40         ` Edgecombe, Rick P
2022-05-24 22:08           ` Luis Chamberlain
2022-05-25  6:01             ` hch
2022-05-20  3:15 ` [PATCH v3 bpf-next 6/8] vmalloc: WARN for set_vm_flush_reset_perms() on huge pages Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 7/8] vmalloc: introduce huge_vmalloc_supported Song Liu
2022-05-20  3:15 ` [PATCH v3 bpf-next 8/8] bpf: simplify select_bpf_prog_pack_size Song Liu

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