Messages in this thread | | | Subject | Re: [PATCH v3] lib/bitmap.c: enhance bitmap syntax | From | Pan Xinhui <> | Date | Sun, 17 Jul 2016 21:50:15 +0800 |
| |
在 16/7/17 16:10, Noam Camus 写道: > From: Noam Camus <noamca@mellanox.com> > > 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.: > <cpus range>%modulo=<range of reminders> > > 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.
> Note that this patch is backward compatible with current syntax. > > Signed-off-by: Noam Camus <noamca@mellanox.com> > --- > 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; > } >
| |