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 39A9B2C17A1; Mon, 2 Feb 2026 19:59:53 +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=1770062396; cv=none; b=qF4Y1L8T5TrmAvsFqRqOsVy4J6TcfrXTNXc1faXvdjQuVaIPtl4RcvaVrHGWJiBrMw9jfGSJw+F/LgfJgdr1xpsE35NPh0WTcC+mhgmK/hRIb0HRW8H3+mnOhR1krW1iZ41GYvDNHNOGx55IOSd7G9zbQS4JywXjUmFvqvv66fw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770062396; c=relaxed/simple; bh=eEU6X/6L7H/3zpIVEJEiFvuFbR2Tsb/isJ7/+9fxYsk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Nbfn/GJ4Q5Amhm+W+4RA3011BEOO2yFa4v3U2Mp8QwSmGMXHLj2aWD2kXHjfHukeTPbzMD3hzYCJ4DS//jB896a9DbJYSIClSbkQCBsoLcLQE4oVEi1CK5ZGV2hHMOX+m2OL879hm77V1f8NQynnTkH98vSOp+NFyPWcuizZjIc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=fzWlhWu2; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="fzWlhWu2" 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=Ijkgu82x5tCkNyZgQnmbEBJphoNEGQgRBkZ7m2AwrGY=; b=fzWlhWu2KNOvni03qgbg5X6xt+ e64YaRpHvUj5sM2HHZiHgNcfRce/ra3GMnADtB23Kpjc4zG8+Lc94UMoiueScO7YzNheOabtIOibK LFDgeTrNBpeDtQltabGi3K3Tc+JM5Ng6vWU2iYY4gaBCb4W484JEpWhLJu2lE36IpjaaSvFZENLNB hUaEPevouUmJZYvvcDGswZzVy46aONuN1tWgRDeo5kOHS0sxjonxHKSnuClDrpXeE869FjMiGGw2+ rSM+NGAUgX6Xd0eZabHVvxDmWEHfjI20xtquzq3gPbEu+unbJbpIvgt06tkSgdEVrv+GlVTVgrnWu /Hi064UQ==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vn05H-0000000Gzcd-2exJ; Mon, 02 Feb 2026 19:59:43 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 2A2853008E2; Mon, 02 Feb 2026 20:59:43 +0100 (CET) Date: Mon, 2 Feb 2026 20:59:43 +0100 From: Peter Zijlstra To: Andrii Nakryiko Cc: Tao Chen , mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, song@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH bpf-next v8 2/3] perf: Refactor get_perf_callchain Message-ID: <20260202195943.GI1282955@noisy.programming.kicks-ass.net> References: <20260126074331.815684-1-chen.dylane@linux.dev> <20260126074331.815684-3-chen.dylane@linux.dev> <20260128091033.GG3372621@noisy.programming.kicks-ass.net> <20260130113150.GB166857@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=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Jan 30, 2026 at 12:04:45PM -0800, Andrii Nakryiko wrote: > > Also, there appears to be no buildid caching what so ever, surely that > > would help some. > > Jiri Olsa proposed caching build id per file or per inode some time > back, there was vehement opposition to it. And doing some locked > global resizable hash that might need to be used from NMI sounds > horrible, tbh. So we have what we have today. See kernel/module/tree_lookup.c and include/linux/rbtree_latch.h :-)