From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1D51249739B; Fri, 18 Sep 2026 07:04:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789715068; cv=none; b=aJrcKYM93JwrYg89MLN14SJfmTGtAqtdagl7HQdL+ELv0jDp9WLmpWsWTPrUDhAUFmRN5lhfatRXfxK9M81Pz4o+5MT/04Ydij9P3XM2OEIK5gcrsddiwlHO/FUj2pPuuNzMAclKagUdkhunzEcNISAsh/HKW+17zsRo4IAGs5g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789715068; c=relaxed/simple; bh=LjBulbBPS4HQ+2+ENfpTJJe7kppwctse0hq8ahYzkC0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=l1/PAnBDhBxN5PCTSVLL4qNBBpjGFiZngwOUewlZ5CtOn4dxeM1sQQJQgWbmnpn7RCs/7zHst63gzwywCee5GpfRLlztQWbiEm1LIRqJaXwSdmeRS+Ymq7rV+cMaeI+fBwyhZASBIH5mMOHhFRPmNrVG30o13S54gxG2hwzuJ9Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P/LKqi2L; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P/LKqi2L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDFB51F000FF; Fri, 18 Sep 2026 07:04:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789715066; bh=h7MrO5kHfs9s9gpQkpstdAXZ31bb0e2lmCQcEqPnDlQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=P/LKqi2LqAKG2z2uozCnUWME8OGZ9RbIIELAHHwTXvdmqJNNhcB+P6+T4o1eQ8bff emGEtPWT0PNKHunU+e67JP0rY4/3Tgr8kyp6GDWN5FCOr2JHeXpqhM1RzrzJHkb9Ew brC89Jmwg9/AeYM1XEAol1WvLn6e+jB9Z2r8WtID8EVVzKhebhWUcARXEcnzhnt6y3 r34S5YxuU4zLWiUFw7Zf3wQagohKhQK4vsCUZTFh3QOxASwCM3MANSEXJOLdQMuvVu 1hUCQ3DHh2wB0WW/fnGCHvw1eL+/L2pnuOVar83DD1+R3aG+zlkAmPp42idM32aMKO /aI0Z7fDCQizQ== Date: Fri, 18 Sep 2026 00:04:24 -0700 From: Namhyung Kim To: Peter Zijlstra Cc: Harry Yoo , Tim Menninger , linux-mm@kvack.org, Chuck Lever , linux-nfs@vger.kernel.org, Jon Curley , Eric Badger , Vlastimil Babka , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [SLUB] nfs_page cmpxchg_double_fail and perf lock perturbation on dual-socket NFS/RDMA Message-ID: References: <20260916232227.4098143-1-tmenninger@everpuredata.com> <20260917152959.GI4121339@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260917152959.GI4121339@noisy.programming.kicks-ass.net> Hello, On Thu, Sep 17, 2026 at 05:29:59PM +0200, Peter Zijlstra wrote: > On Thu, Sep 17, 2026 at 03:10:47PM +0100, Harry Yoo wrote: > > ... now I realize we need to add PERFORMANCE EVENTS SUBSYSTEM folks > > as well ;-) > > > > Hmm, sounds like perf lock is somehow triggering slab allocations > > and interfering the workload. > > perf should not have runtime memory allocation, its build to run from > NMI context. It can allocate some memory on event creation and the like, > but once its on, there should be no more allocations happening. Right, perf lock record command will save the event info to a ring buffer without allocation. It may lose some events when the buffer is full though. Thanks, Namhyung