From: Luis Chamberlain <mcgrof@kernel.org>
To: Aaron Lu <aaron.lu@intel.com>, Davidlohr Bueso <dave@stgolabs.net>
Cc: Song Liu <song@kernel.org>,
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,
rick.p.edgecombe@intel.com, kernel-team@fb.com
Subject: Re: [PATCH v4 bpf-next 0/8] bpf_prog_pack followup
Date: Mon, 20 Jun 2022 11:31:39 -0700 [thread overview]
Message-ID: <YrC9CyOPamPneUOT@bombadil.infradead.org> (raw)
In-Reply-To: <YrBV8darrlmUnrHR@ziqianlu-Dell-Optiplex7000>
On Mon, Jun 20, 2022 at 07:11:45PM +0800, Aaron Lu wrote:
> Hi Song,
>
> On Fri, May 20, 2022 at 04:57:50PM -0700, Song Liu wrote:
>
> ... ...
>
> > The primary goal of bpf_prog_pack is to reduce iTLB miss rate and reduce
> > direct memory mapping fragmentation. This leads to non-trivial performance
> > improvements.
> >
> > For our web service production benchmark, bpf_prog_pack on 4kB pages
> > gives 0.5% to 0.7% more throughput than not using bpf_prog_pack.
> > bpf_prog_pack on 2MB pages 0.6% to 0.9% more throughput than not using
> > bpf_prog_pack. Note that 0.5% is a huge improvement for our fleet. I
> > believe this is also significant for other companies with many thousand
> > servers.
> >
>
> I'm evaluationg performance impact due to direct memory mapping
> fragmentation
BTW how exactly are you doing this?
Luis
> and seeing the above, I wonder: is the performance improve
> mostly due to prog pack and hugepage instead of less direct mapping
> fragmentation?
>
> I can understand that when progs are packed together, iTLB miss rate will
> be reduced and thus, performance can be improved. But I don't see
> immediately how direct mapping fragmentation can impact performance since
> the bpf code are running from the module alias addresses, not the direct
> mapping addresses IIUC?
>
> I appreciate it if you can shed some light on performance impact direct
> mapping fragmentation can cause, thanks.
next prev parent reply other threads:[~2022-06-20 18:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-20 23:57 [PATCH v4 bpf-next 0/8] bpf_prog_pack followup Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 1/8] bpf: fill new bpf_prog_pack with illegal instructions Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 2/8] x86/alternative: introduce text_poke_set Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 3/8] bpf: introduce bpf_arch_text_invalidate for bpf_prog_pack Song Liu
2022-05-24 7:20 ` Mike Rapoport
2022-05-20 23:57 ` [PATCH v4 bpf-next 4/8] module: introduce module_alloc_huge Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 5/8] bpf: use module_alloc_huge for bpf_prog_pack Song Liu
2022-05-24 7:22 ` Mike Rapoport
2022-05-24 16:42 ` Edgecombe, Rick P
2022-06-17 23:05 ` Edgecombe, Rick P
2022-05-20 23:57 ` [PATCH v4 bpf-next 6/8] vmalloc: WARN for set_vm_flush_reset_perms() on huge pages Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 7/8] vmalloc: introduce huge_vmalloc_supported Song Liu
2022-05-20 23:57 ` [PATCH v4 bpf-next 8/8] bpf: simplify select_bpf_prog_pack_size Song Liu
2022-05-23 21:20 ` [PATCH v4 bpf-next 0/8] bpf_prog_pack followup patchwork-bot+netdevbpf
2022-06-20 11:11 ` Aaron Lu
2022-06-20 16:03 ` Song Liu
2022-06-21 1:31 ` Aaron Lu
2022-06-21 2:51 ` Song Liu
2022-06-21 3:25 ` Aaron Lu
2022-06-20 18:31 ` Luis Chamberlain [this message]
2022-06-21 1:45 ` Aaron Lu
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