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

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Message-ID: <Z_fbFcT3gxNK_dWr@google.com>
Date: Thu, 10 Apr 2025 07:52:05 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Kevin Tian <kevin.tian@...el.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Alex Williamson <alex.williamson@...hat.com>, 
	"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

On Thu, Apr 10, 2025, Kevin Tian wrote:
> > 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@tencent.com

I linked Like's submission here, which has his numbers.  Would it be helpful to
explictly call this out in the meat of the changelog?