From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751107AbcGQN64 (ORCPT ); Sun, 17 Jul 2016 09:58:56 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:7181 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750866AbcGQN6z (ORCPT ); Sun, 17 Jul 2016 09:58:55 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: xinhui@linux.vnet.ibm.com Subject: Re: [PATCH v3] lib/bitmap.c: enhance bitmap syntax To: Noam Camus , decot@googlers.com References: <1468737234-29232-1-git-send-email-noamca@mellanox.com> <1468743057-29498-1-git-send-email-noamca@mellanox.com> <3d1f92a0-4c67-54de-11d6-927d88e8de7b@linux.vnet.ibm.com> Cc: ben@decadent.org.uk, davem@davemloft.net, akpm@linux-foundation.org, linux-kernel@vger.kernel.org From: Pan Xinhui Date: Sun, 17 Jul 2016 21:59:21 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <3d1f92a0-4c67-54de-11d6-927d88e8de7b@linux.vnet.ibm.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16071713-0012-0000-0000-0000102EAB34 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16071713-0013-0000-0000-000043BA991D Message-Id: <06d3f797-2de6-42a2-c356-db086e14836c@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-17_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607170175 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 16/7/17 21:50, Pan Xinhui дµÀ: > > > ÔÚ 16/7/17 16:10, Noam Camus дµÀ: >> From: Noam Camus >> >> Today there are platforms with many CPUs (up to 4K). >> Trying to boot only part of the CPUs may result in too long string. >> >> For example lets take NPS platform that is part of arch/arc. >> This platform have SMP system with 256 cores each with >> 16 HW threads (SMT machine) where HW thread appears as CPU to the kernel. >> In this example there is total of 4K CPUs. >> When one tries to boot only part of the HW threads from each core the >> string representing the map may be long... >> For example if for sake of performance we decided to boot only first half >> of HW threads of each core the map will look like: >> 0-7,16-23,32-39,...,4080-4087 >> >> This patch introduce new syntax to accommodate with such use case. >> I added an optional postfix to a range of CPUs which will choose >> according to given modulo the desired range of reminders i.e.: >> %modulo= >> >> For example, above map can be described in new syntax like this: >> 0-4095%16=0-7 >> > > I really think it is better to implement one function to generic a string which contanis the cpus you want to boot on, then pass this string to __bitmap_parselist. > sorry, typos. generic -> generate. >> Note that this patch is backward compatible with current syntax. >> >> Signed-off-by: Noam Camus >> --- >> Any sugestions for simpler syntax which keeps its generality are welcomed. >> >> Change Log: >> V2: Fix typo in example at function header for __bitmap_parselist() >> V3: Fix typo in commit log and also typo at example >> --- >> lib/bitmap.c | 44 ++++++++++++++++++++++++++++++++++++++++---- >> 1 files changed, 40 insertions(+), 4 deletions(-) >> >> diff --git a/lib/bitmap.c b/lib/bitmap.c >> index c66da50..bccfd87 100644 >> --- a/lib/bitmap.c >> +++ b/lib/bitmap.c >> @@ -496,6 +496,9 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf); >> * ranges. Consecutively set bits are shown as two hyphen-separated >> * decimal numbers, the smallest and largest bit numbers set in >> * the range. >> + * Optionally each range can be postfixed to denote that only parts of it >> + * should be set. The parts are the range of reminders modulo some value. >> + * i.e. range%mod=rem_range e.g. 0-1023%256=0-1 ==> 0,1,256,257,512,513,768,769 >> * >> * Returns 0 on success, -errno on invalid input strings. >> * Error values: >> @@ -507,12 +510,14 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, >> int is_user, unsigned long *maskp, >> int nmaskbits) >> { >> - unsigned a, b; >> + unsigned int a, b, old_a, old_b, mod_val, mod_a, mod_b; >> int c, old_c, totaldigits, ndigits; >> const char __user __force *ubuf = (const char __user __force *)buf; >> int at_start, in_range; >> >> totaldigits = c = 0; >> + old_a = old_b = 0; >> + mod_val = mod_a = mod_b = 0; >> bitmap_zero(maskp, nmaskbits); >> do { >> at_start = 1; >> @@ -547,6 +552,23 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, >> if ((totaldigits != ndigits) && isspace(old_c)) >> return -EINVAL; >> >> + if (c == '=') { >> + mod_val = a; >> + at_start = 1; >> + in_range = 0; >> + a = b = 0; >> + continue; >> + } >> + >> + if (c == '%') { >> + old_a = a; >> + old_b = b; >> + at_start = 1; >> + in_range = 0; >> + a = b = 0; >> + continue; >> + } >> + >> if (c == '-') { >> if (at_start || in_range) >> return -EINVAL; >> @@ -567,17 +589,31 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, >> } >> if (ndigits == totaldigits) >> continue; >> + if (mod_val) { >> + mod_a = a; >> + mod_b = b; >> + a = old_a; >> + b = old_b; >> + old_a = old_b = 0; >> + } >> /* if no digit is after '-', it's wrong*/ >> if (at_start && in_range) >> return -EINVAL; >> - if (!(a <= b)) >> + if (!(a <= b) || !(mod_a <= mod_b)) >> return -EINVAL; >> - if (b >= nmaskbits) >> + if (b >= nmaskbits || (mod_val && (mod_b >= mod_val))) >> return -ERANGE; >> while (a <= b) { >> - set_bit(a, maskp); >> + if (mod_val) { >> + unsigned int rem = a % mod_val; >> + >> + if (rem >= mod_a && rem <= mod_b) >> + set_bit(a, maskp); >> + } else >> + set_bit(a, maskp); >> a++; >> } >> + mod_val = mod_a = mod_b = 0; >> } while (buflen && c == ','); >> return 0; >> } >>