linux-kernel - Re: [PATCH v4 0/2] nvme/pci: PRP list DMA pool partitioning

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Message-ID: <aAgcLf-X_kWTPRGZ@kbusch-mbp.dhcp.thefacebook.com>
Date: Tue, 22 Apr 2025 16:46:05 -0600
From: Keith Busch <kbusch@...nel.org>
To: Caleb Sander Mateos <csander@...estorage.com>
Cc: Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
	Sagi Grimberg <sagi@...mberg.me>,
	Kanchan Joshi <joshi.k@...sung.com>, linux-nvme@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/2] nvme/pci: PRP list DMA pool partitioning

On Tue, Apr 22, 2025 at 03:04:37PM -0700, Caleb Sander Mateos wrote:
> On Tue, Apr 22, 2025 at 10:48 AM Keith Busch <kbusch@...nel.org> wrote:
> >
> > On Tue, Apr 22, 2025 at 10:19:57AM -0600, Caleb Sander Mateos wrote:
> > > This reduces the _raw_spin_lock_irqsave overhead by about half, to
> > > 1.2%.
> >
> > Could you try this atop your series? I hope to see if we can squeeze a
> > little more out by keeping the spinlock and list links local to the node
> > using them.
> 
> That does help save some CPU time in dma_pool_alloc too. It's down
> from 0.87% of CPU time to 0.52% while doing 5% more IOPS. I'll include
> your patch (with a few tweaks) in a v5 of this series. Hopefully
> you're okay if I include your Signed-off-by.

Awesome! And yes, totally okay with me to fold the patch into your
series.