From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794349416; b=QJVuN9F/ZdiFcnM/jtIQIl7q88eiuGeidn4X+NGLyFDtVvnKdPsmc/wCmsfd6p+rA6eZ jnzsSDKTdjEOZZjj8vbYmiKaewz4zUXKh3WMRdNwbJ3GxeqCxs5m1TXrMSXnOwHzg2EV8 HAVXdHWBc50TVUuPS9loBjm8PHWSzr23QBSdOv3t9nNf3rU5YKQ5/8RYwgkWNq42kJQH6 E//6I0PntOP/1OTKGzNSHXTqa1HEh3QoKuR6FZ2n/t0I+Z43E+NHEJIrAlHtrF00iaMKT m/gH7YXyPPmkiVnEvqLSnzobEQZxAEdFueJrW/oJLYR+c4h/wMEM3POL/ljXOwdDqKQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794349416; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=IveUz8MhtTVNYskK0J4Zd2urfS4oEQ2T9uY8gl0ZTmY=; b=T4bNl+8k8SBe1FXPuzE17dIlIjmP9JlwVhF8iowgJ22FcnIir3TfTumydg6GB0zzaS0F i6IOJTD3N/Cw+olS0OraitkH2dHCOSWSZ9cd2k5Vpf3c6646BvnypI/P1UK9N63H5mIzE Lw21lRnQnpLL8UMbUJ6tBj27AqobmhNVMvJUMlkVOp9cuswu6wnwmGRqThOcCkGhuSBu2 69eSECz1zQZHDk63JFtgV+5b9IN5QVt24LSNgByjcdAxfti8wgzlgW7Xa1QlAZ+3ypYxb IFYevu0GW3vOk42xGPFgru80FQ/XFXEzVZ4BTnWbvKM+3qBY+3wVUzn7XV4oI7bS/Lg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=UC5AhGS2; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3FBD606A320 for ; Tue, 10 Nov 2026 22:23:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=UC5AhGS2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21FB31F008A2; Tue, 10 Nov 2026 22:23:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794349415; bh=IveUz8MhtTVNYskK0J4Zd2urfS4oEQ2T9uY8gl0ZTmY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=UC5AhGS27DFwxdyqUyc5AE+I3jDSsv2lYpZuyLV2rgFv9Iaa7u8cIMRLM6bMu3ST/ lFHCsdrDEaJAxH3eb9WxANQxys916eNgsIm7+98m6REqGQODfkkeXhW2R6T6Yb67nV ztPGtvo0Q+pGBx6OpSZqRJlebsA2YKRcO0JAWOzC1jYXzJqY9AnYOQAA3JgNyMrko9 cwKt0+ftKz8KN8FbRxKq/ig256KvihzPMzajAjbQRwBvvEJdp+AjuOlHhk2mJ+aEhk XhBfgdG/SwF7vT4bSwpVhO0L2ycBpHq3c1xbQQABixtVWRrvwe0hdyCsqLK5TQWr+s 7adauv4k/o4Iw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v3 11/20] perf demangle: Add fast-path prefix checks for Rust and Java demanglers Reply-To: sashiko-reviews@lists.linux.dev To: "Ian Rogers" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261110220803.2503416-12-irogers@google.com> References: <20261027231513.816148-1-irogers@google.com> <20261110220803.2503416-1-irogers@google.com> <20261110220803.2503416-12-irogers@google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 10 Nov 2026 22:23:34 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > During DSO symbol loading in dso__load_sym_internal(), dso__demangle_sym() > is called for every ELF symbol. Both rust_demangle_demangle() and > java_demangle_sym() previously performed string searches or buffer > allocations before checking whether the symbol name could possibly be a > mangled Rust or Java symbol, adding unnecessary overhead on plain C > symbols. >=20 > Add fast-path prefix checks in dso__demangle_sym() before calling > rust_demangle_demangle() (using strstarts() for '_ZN', 'ZN', '__ZN', > '_R', 'R', or '__R', keeping demangle-rust-v0.c unmodified relative to > upstream rustc-demangle) and in java_demangle_sym() (requiring 'L', ';', > '(', and ')') to reject non-Rust and non-Java symbol names immediately. >=20 > Using 'perf bench internals symbols': >=20 > Before (perf binary): > Average DSO load + sort: 7.348 msec (+- 0.069 msec) > After (perf binary, -4.2%): > Average DSO load + sort: 7.041 msec (+- 0.051 msec) >=20 > Before (libLLVM.so.21.1): > Average DSO load + sort: 81.196 msec (+- 0.780 msec) > After (libLLVM.so.21.1, -3.2%): > Average DSO load + sort: 78.599 msec (+- 0.857 msec) >=20 > Signed-off-by: Ian Rogers Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261110220803.2503= 416-1-irogers@google.com?part=3D11