linux-kernel - Re: [PATCH v2 1/2] USB: core: add a memory pool to urb for host-controller private data

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Message-ID: <d00a5238-90e7-4651-aaae-2919848be33b@suse.com>
Date: Wed, 14 May 2025 11:34:21 +0200
From: Oliver Neukum <oneukum@...e.com>
To: Greg KH <gregkh@...uxfoundation.org>, David Wang <00107082@....com>
Cc: mathias.nyman@...el.com, stern@...land.harvard.edu,
 linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 1/2] USB: core: add a memory pool to urb for
 host-controller private data

On 14.05.25 09:29, Greg KH wrote:
  
> No, this isn't necessarily true at all.  Allocations are fast, and if we
> free/allocate things quickly, it's even faster.  USB is limited by the
> hardware throughput, which is _very_ slow compared to memory accesses of
> the allocator.

If and only if we do not trigger disk IO. If you really want to give this patch
a good performance testing you'd have to do it under memory pressure.

	Regards
		Oliver