linux-kernel - Re: [PATCH v2 bpf 3/3] bpf: use vmalloc with VM_ALLOW_HUGE_VMAP for bpf_prog

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Date:   Wed, 13 Apr 2022 15:51:46 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To:     "song@...nel.org" <song@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "hch@...radead.org" <hch@...radead.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "rppt@...nel.org" <rppt@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "andrii@...nel.org" <andrii@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "imbrenda@...ux.ibm.com" <imbrenda@...ux.ibm.com>
Subject: Re: [PATCH v2 bpf 3/3] bpf: use vmalloc with VM_ALLOW_HUGE_VMAP for
 bpf_prog_pack

CC Mike, who has been working on a direct map fragmentation solution.
[0]

On Tue, 2022-04-12 at 14:00 -0700, Song Liu wrote:
> Since I am still learning the vmalloc/module_alloc code, I think I am
> not really capable of commenting on the direction. From our use
> cases, we do see performance hit due to large number of BPF
> program fragmenting the page table. Kernel module, OTOH, is not
> too big an issue for us, as we usually build hot modules into the
> kernel. That being said, we are interested in making the huge page
> interface general for BPF program and kernel module. We can
> commit resources to this effort.

That sounds great. Please feel free to loop me in if you do.


[0] 
https://lore.kernel.org/lkml/20220127085608.306306-1-rppt@kernel.org/