linux-kernel - Re: [PATCH v8 04/23] slab: add sheaf support for batching kfree

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Message-ID: <aS07_pFAtVCsNIXd@hyeyoo>
Date: Mon, 1 Dec 2025 15:55:58 +0900
From: Harry Yoo <harry.yoo@...cle.com>
To: Jon Hunter <jonathanh@...dia.com>
Cc: Daniel Gomez <da.gomez@...nel.org>, Vlastimil Babka <vbabka@...e.cz>,
        Suren Baghdasaryan <surenb@...gle.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Christoph Lameter <cl@...two.org>,
        David Rientjes <rientjes@...gle.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Uladzislau Rezki <urezki@...il.com>,
        Sidhartha Kumar <sidhartha.kumar@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
        maple-tree@...ts.infradead.org, linux-modules@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Aaron Tomlin <atomlin@...mlin.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v8 04/23] slab: add sheaf support for batching
 kfree_rcu() operations

On Fri, Nov 28, 2025 at 08:57:28AM +0000, Jon Hunter wrote:
> 
> On 27/11/2025 12:48, Harry Yoo wrote:
> 
> ...
> 
> > > > I have been looking into a regression for Linux v6.18-rc where time taken to
> > > > run some internal graphics tests on our Tegra234 device has increased from
> > > > around 35% causing the tests to timeout. Bisect is pointing to this commit
> > > > and I also see we have CONFIG_KVFREE_RCU_BATCHED=y.
> > > 
> > > Thanks for reporting! Uh, this has been put aside while I was busy working
> > > on other stuff... but now that we have two people complaining about this,
> > > I'll allocate some time to investigate and improve it.
> > > 
> > > It'll take some time though :)
> > 
> > By the way, how many CPUs do you have on your system, and does your
> > kernel have CONFIG_CODE_TAGGING enabled?
> 
> For this device there are 12 CPUs. I don't see CONFIG_CODE_TAGGING enabled.

Thanks! Then it's probably due to kmem_cache_destroy().
Please let me know this patch improves your test execution time.

https://lore.kernel.org/linux-mm/20251128113740.90129-1-harry.yoo@oracle.com/

-- 
Cheers,
Harry / Hyeonggon