From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 A431B13B797; Tue, 23 Sep 2025 10:01:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758621710; cv=none; b=BuhvGye+aSaosVYTK/in0e5FSv8ToBwuEo/y1epvP6XtN0w0HOfkqqymoQih9fUCBgYfxHJUOc6IdT+h+9HPskt2meeE3uKRiOSsHdg6dPSTKke2kQqbGp7/qGStpl0e14IgiB6LvBRYWCdMYFPeD75strelpFh5V6HeTSYIHOo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758621710; c=relaxed/simple; bh=H66pboQoJo8IfGy7SEDJFTFcAXDk7qmARTyg7LlRVCg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nRfJgmRCBldGsakVxZdXVN965zt5AySm+gInG92z9uN8tDP94y/rohzOaxs0Z0AHDpOkVJUuaX6S9Y3BnrHdTt5MoBEyRI0/ACP/kz9vKif6anr/cD8I3rv1VjJuUsXSDtLINXRN6k1wv463V+p1xUYq8NPG6ZJtIgYjAd7QnK0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=cwlNGojy; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cwlNGojy" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ZJB/cAN/NZ934Eo6FWgaO0JE3BoJmkJPozs04WZwYr8=; b=cwlNGojyeXZkx1IDwcDvXrJ1w0 Ho0qAHQV8sMu2BD2cf4CHBuh83EGUUHL0rgtwpme1MxXaYg9y5xwEHe1MjE3HHTdgjsnmaH10lnsY CBwRv1ksl3B3VuJyiPmwqB121G9AVfp5H9Q2MFDRwJV9A1+xKGb9Lk10NpJ86X14KkZ0riYgfK0L5 YcXj7QJs5S7mUhIVfkmlBk6ghEaTNs/HpPOIzOAFIkZM4+RzOlmZG4Pyw4afjuqm5Qi+ZqCR8Euz+ lVtmbn5F//doA+RkSYiQnZ9fSa6J+aengGUpvfH4aENuCuv/UJVff83Zygzwpgcc8/dMT5Nh8q/5C P1zZaBeA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v0zq6-00000009YwE-1iUF; Tue, 23 Sep 2025 10:01:39 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6334830049C; Tue, 23 Sep 2025 12:01:37 +0200 (CEST) Date: Tue, 23 Sep 2025 12:01:37 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Florian Weimer , Sam James , Kees Cook , Carlos O'Donell Subject: Re: [RESEND][PATCH v15 2/4] perf: Support deferred user callchains Message-ID: <20250923100137.GC3419281@noisy.programming.kicks-ass.net> References: <20250908171412.268168931@kernel.org> <20250908171524.605637238@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250908171524.605637238@kernel.org> On Mon, Sep 08, 2025 at 01:14:14PM -0400, Steven Rostedt wrote: > + /* > + * All accesses related to the event are within the same RCU section in > + * perf_event_callchain_deferred(). The RCU grace period before the > + * event is freed will make sure all those accesses are complete by then. > + */ > + rcuwait_wait_event(&event->pending_unwind_wait, !event->pending_unwind_callback, TASK_UNINTERRUPTIBLE); You need a narrower terminal, this is again excessive. I mostly code with my screen split in 4 columns (3 if I can't find my glasses), and that gets me around 90 character columns. > + if (event->attr.defer_callchain) > + init_task_work(&event->pending_unwind_work, > + perf_event_callchain_deferred); And let me hand you a bucket of {}, I've heard they're getting expensive over in the US due to this tariff nonsense :-)