From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1921) id 869CA385415F; Mon, 11 Jul 2022 11:55:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 869CA385415F Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Sebastian Huber To: newlib-cvs@sourceware.org Subject: [newlib-cygwin] Correctly measure system load averages > 1024 X-Act-Checkin: newlib-cygwin X-Git-Author: Alan Somers X-Git-Refname: refs/heads/master X-Git-Oldrev: 0ed668df2cdd29abfb94de726745e43243c787d0 X-Git-Newrev: 27dfb5f33fa4954f6278ae8b82584c269fb6e6ef Message-Id: <20220711115535.869CA385415F@sourceware.org> Date: Mon, 11 Jul 2022 11:55:35 +0000 (GMT) X-BeenThere: newlib-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Newlib GIT logs List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jul 2022 11:55:35 -0000 https://sourceware.org/git/gitweb.cgi?p=3Dnewlib-cygwin.git;h=3D27dfb5f33fa= 4954f6278ae8b82584c269fb6e6ef commit 27dfb5f33fa4954f6278ae8b82584c269fb6e6ef Author: Alan Somers Date: Thu May 5 15:35:23 2022 -0600 Correctly measure system load averages > 1024 =20 The old fixed-point arithmetic used for calculating load averages had an overflow at 1024. So on systems with extremely high load, the observed load average would actually fall back to 0 and shoot up again, creating a kind of sawtooth graph. =20 Fix this by using 64-bit math internally, while still reporting the load average to userspace as a 32-bit number. =20 Sponsored by: Axcient Reviewed by: imp Differential Revision: https://reviews.freebsd.org/D35134 Diff: --- newlib/libc/sys/rtems/include/sys/param.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/newlib/libc/sys/rtems/include/sys/param.h b/newlib/libc/sys/rt= ems/include/sys/param.h index c346453bf..9596ecf52 100644 --- a/newlib/libc/sys/rtems/include/sys/param.h +++ b/newlib/libc/sys/rtems/include/sys/param.h @@ -248,12 +248,12 @@ * Scale factor for scaled integers used to count %cpu time and load avgs. * * The number of CPU `tick's that map to a unique `%age' can be expressed - * by the formula (1 / (2 ^ (FSHIFT - 11))). The maximum load average that - * can be calculated (assuming 32 bits) can be closely approximated using - * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15). + * by the formula (1 / (2 ^ (FSHIFT - 11))). Since the intermediate + * calculation is done with 64-bit precision, the maximum load average tha= t can + * be calculated is approximately 2^32 / FSCALE. * * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age', - * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024. + * FSHIFT must be at least 11. This gives a maximum load avg of 2 million. */ #define FSHIFT 11 /* bits to right of fixed binary point */ #define FSCALE (1<