linux-kernel - RE: [PATCH 7/7] irqbypass: Use xarray to track producers and consumers

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Message-ID: <BN9PR11MB52769DDEE406798D028BC17D8CB72@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Thu, 10 Apr 2025 07:38:15 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Sean Christopherson <seanjc@...gle.com>, "Michael S. Tsirkin"
	<mst@...hat.com>, Jason Wang <jasowang@...hat.com>, Paolo Bonzini
	<pbonzini@...hat.com>, Alex Williamson <alex.williamson@...hat.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"virtualization@...ts.linux.dev" <virtualization@...ts.linux.dev>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Oliver Upton
	<oliver.upton@...ux.dev>, David Matlack <dmatlack@...gle.com>, Like Xu
	<like.xu.linux@...il.com>, Yong He <alexyonghe@...cent.com>
Subject: RE: [PATCH 7/7] irqbypass: Use xarray to track producers and
 consumers

> From: Sean Christopherson <seanjc@...gle.com>
> Sent: Saturday, April 5, 2025 5:15 AM
> 
> Track IRQ bypass produsers and consumers using an xarray to avoid the
> O(2n)
> insertion time associated with walking a list to check for duplicate
> entries, and to search for an partner.
> 
> At low (tens or few hundreds) total producer/consumer counts, using a list
> is faster due to the need to allocate backing storage for xarray.  But as
> count creeps into the thousands, xarray wins easily, and can provide
> several orders of magnitude better latency at high counts.  E.g. hundreds
> of nanoseconds vs. hundreds of milliseconds.

add a link to the original data collected by Like.

> 
> Cc: Oliver Upton <oliver.upton@...ux.dev>
> Cc: David Matlack <dmatlack@...gle.com>
> Cc: Like Xu <like.xu.linux@...il.com>
> Reported-by: Yong He <alexyonghe@...cent.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217379
> Link: https://lore.kernel.org/all/20230801115646.33990-1-
> likexu@...cent.com
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Kevin Tian <kevin.tian@...el.com>