From: <dan.j.williams@intel.com>
To: "David Hildenbrand (Red Hat)" <david@kernel.org>,
Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Li Zhe <lizhe.67@bytedance.com>, <akpm@linux-foundation.org>,
<ankur.a.arora@oracle.com>, <fvdl@google.com>,
<joao.m.martins@oracle.com>, <linux-kernel@vger.kernel.org>,
<linux-mm@kvack.org>, <mhocko@suse.com>, <mjguzik@gmail.com>,
<muchun.song@linux.dev>, <osalvador@suse.de>,
<raghavendra.kt@amd.com>, <linux-cxl@vger.kernel.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Gregory Price <gourry@gourry.net>,
Dan Williams <dan.j.williams@intel.com>, <zhanjie9@hisilicon.com>,
<wangzhou1@hisilicon.com>
Subject: Re: [PATCH v2 0/8] Introduce a huge-page pre-zeroing mechanism
Date: Thu, 15 Jan 2026 12:16:06 -0800 [thread overview]
Message-ID: <69694b06835e_34d2a100b3@dwillia2-mobl4.notmuch> (raw)
In-Reply-To: <23513e86-0769-4f3f-b90b-22273343a03c@kernel.org>
David Hildenbrand (Red Hat) wrote:
[..]
> > Give me a list of 1Gig pages and this stuff becomes much more efficient
> > than anything the CPU can do.
>
> Right, and ideally we'd implement any such mechanisms in a way that more
> parts of the kernel can benefit, and not just an unloved in-memory
> file-system that most people just want to get rid of as soon as we can :)
CPUs have tended to eat the value of simple DMA offload operations like
copy/zero over time.
In the case of this patch there is no async-offload benefit because
userspace is already charged with spawning more threads if it wants more
parallelism.
For sync-offload one engine may be able to beat a single CPU, but now
you have created bandwidth contention problems with a component that is
less responsive to the scheduler.
Call me skeptical.
Signed, someone with async_tx and dmaengine battle scars.
next prev parent reply other threads:[~2026-01-15 20:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <9daa39e6-9653-45cc-8c00-abf5f3bae974@kernel.org>
[not found] ` <20260115093641.44404-1-lizhe.67@bytedance.com>
[not found] ` <83798495-915b-4a5d-9638-f5b3de913b71@kernel.org>
2026-01-15 11:57 ` [PATCH v2 0/8] Introduce a huge-page pre-zeroing mechanism Jonathan Cameron
2026-01-15 17:08 ` David Hildenbrand (Red Hat)
2026-01-15 20:16 ` dan.j.williams [this message]
2026-01-15 20:22 ` David Hildenbrand (Red Hat)
2026-01-15 22:30 ` Ankur Arora
2026-01-20 6:27 ` Li Zhe
2026-01-20 9:47 ` David Laight
2026-01-20 10:39 ` Li Zhe
2026-01-20 18:18 ` Gregory Price
2026-01-20 18:38 ` Gregory Price
2026-01-20 19:30 ` David Laight
2026-01-20 19:52 ` Gregory Price
2026-01-21 8:03 ` Li Zhe
2026-01-21 12:41 ` David Hildenbrand (Red Hat)
2026-01-21 12:32 ` David Hildenbrand (Red Hat)
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