From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762836Ab2KBNjA (ORCPT ); Fri, 2 Nov 2012 09:39:00 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:33788 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757847Ab2KBNfB (ORCPT ); Fri, 2 Nov 2012 09:35:01 -0400 X-Authority-Analysis: v=2.0 cv=dvhZ+ic4 c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=6vGdCfBhtWsA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=pwcfKUQqO6QA:10 a=20KFwNOVAAAA:8 a=a5u33tJDVs5hvKNU0BwA:9 a=QEXdDO2ut3YA:10 a=jEp0ucaQiEUA:10 a=Zh68SRI7RUMA:10 a=jeBq3FmKZ4MA:10 a=iZOrWjGvEBJJjj9SibkA:9 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.115.198 Message-Id: <20121102133458.770378926@goodmis.org> User-Agent: quilt/0.60-1 Date: Fri, 02 Nov 2012 09:32:57 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , Peter Zijlstra , Thomas Gleixner Subject: [PATCH 05/22] tracing: Expand ring buffer when trace_printk() is used References: <20121102133251.998500247@goodmis.org> Content-Disposition: inline; filename=0005-tracing-Expand-ring-buffer-when-trace_printk-is-used.patch Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="00GvhwF7k39YY" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --00GvhwF7k39YY Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: Steven Rostedt Since tracing is not used by 99% of Linux users, even though tracing may be configured in, it does not make sense to allocate 1.4 Megs per CPU for the ring buffers if they are not used. Thus, on boot up the ring buffers are set to a minimal size until something needs the and they are expanded. This works well for events and tracers (function, etc), but for the asynchronous use of trace_printk() which can write to the ring buffer at any time, does not expand the buffers. On boot up a check is made to see if any trace_printk() is used to see if the trace_printk() temp buffer pages should be allocated. This same code can be used to expand the buffers as well. Suggested-by: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 36c213f..a5411b7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1571,6 +1571,9 @@ void trace_printk_init_buffers(void) =20 pr_info("ftrace: Allocated trace_printk buffers\n"); =20 + /* Expand the buffers to set size */ + tracing_update_buffers(); + buffers_allocated =3D 1; } =20 @@ -3030,6 +3033,10 @@ static int __tracing_resize_ring_buffer(unsigned lon= g size, int cpu) */ ring_buffer_expanded =3D 1; =20 + /* May be called before buffers are initialized */ + if (!global_trace.buffer) + return 0; + ret =3D ring_buffer_resize(global_trace.buffer, size, cpu); if (ret < 0) return ret; --=20 1.7.10.4 --00GvhwF7k39YY Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAABAgAGBQJQk8wCAAoJEOdOSU1xswtMz48IAIuVjc7YYzGcIfx38ncqJeUJ 5pvqmkaCA4HOU40AEbkviuIRSE1n4p2XDnEhiYr9eAu68PuhIriSTNBVsQWweUMo vOEiDuiG1rCS+VVx/AkKNi6+pgsKopIvZwa1e/ZhoEwNHCjafqN07HtWHpfzbu4+ hMFS29cN3zUjSW+83tcQ+gHUHGuh1ljBvEiiw/6VdmnhFkM99f5x3yJgjMiFngyv W3oW0++lTrijqAMAmIo8cIYyNtc/fexZlH8P+iXbZPR4NVLz5c3Z/UYAbHlO80Yx a2mjULUjVm2WlzgoMv1hOkv1CpNM8tNvh10SX76l1vm8ZE+qlPVsvf+JAhFKQPE= =HZ2o -----END PGP SIGNATURE----- --00GvhwF7k39YY--