From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43862) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ffAJK-0005vT-EC for qemu-devel@nongnu.org; Mon, 16 Jul 2018 16:41:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ffAJJ-000077-NS for qemu-devel@nongnu.org; Mon, 16 Jul 2018 16:41:34 -0400 Received: from mail-oi0-x242.google.com ([2607:f8b0:4003:c06::242]:44554) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1ffAJJ-00006l-Hm for qemu-devel@nongnu.org; Mon, 16 Jul 2018 16:41:33 -0400 Received: by mail-oi0-x242.google.com with SMTP id s198-v6so77383892oih.11 for ; Mon, 16 Jul 2018 13:41:33 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20180716195851.0FE177456B7@zero.eik.bme.hu> References: <20180716195851.0FE177456B7@zero.eik.bme.hu> From: Peter Maydell Date: Mon, 16 Jul 2018 21:41:12 +0100 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: Re: [Qemu-devel] [PATCH] Do not enable QOM debugging by default List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: BALATON Zoltan Cc: QEMU Developers , QEMU Trivial , Paolo Bonzini On 16 July 2018 at 20:47, BALATON Zoltan wrote: > Commit 3556c233d 5 years ago added an option to disable QOM debugging, > noting that it can have high performance cost but left the default to on. > Change the default to off and only enable it when debugging is requested > to avoid the performance penalty for those compiling without debug options. > > Signed-off-by: BALATON Zoltan Looking at the code, doesn't this disable all the type checking on the QOM casts? That is not something I think we should drop, in the same way that we do not disable assert()s even in the non-debug build. Is this coming up as significant in profiling? In the past we've done some special casing if there are particular QOM casts in hot paths that use significant runtime. thanks -- PMM