| Message ID | 20180918152923.24824-3-lbloch@janustech.com |
|---|---|
| State | New |
| Headers | show |
| Series | Take the image size into account when allocating the L2 cache | expand |
On Tue 18 Sep 2018 05:29:16 PM CEST, Leonid Bloch wrote: > Adding a lookup table for the powers of two, with the appropriate size > prefixes. This is needed when a size has to be stringified, in which > case something like '(1 * KiB)' would become a literal '(1 * (1L << > 10))' string. Powers of two are used very often for sizes, so such a > table will also make it easier and more intuitive to write them. I wonder in what cases you want to stringify those literals... if it's something that you want to show the user you either: a) know the value in advance, and then you probably want to show "4 GiB" instead of "4294967296 bytes" b) don't know the value in advance (it's a variable), but then you can't use these macros. Am I missing anything? Berto
On 9/21/18 3:17 PM, Alberto Garcia wrote: > On Tue 18 Sep 2018 05:29:16 PM CEST, Leonid Bloch wrote: >> Adding a lookup table for the powers of two, with the appropriate size >> prefixes. This is needed when a size has to be stringified, in which >> case something like '(1 * KiB)' would become a literal '(1 * (1L << >> 10))' string. Powers of two are used very often for sizes, so such a >> table will also make it easier and more intuitive to write them. > > I wonder in what cases you want to stringify those literals... if it's > something that you want to show the user you either: > > a) know the value in advance, and then you probably want to show > "4 GiB" instead of "4294967296 bytes" Then the value will need to be set in two places at any future change. > > b) don't know the value in advance (it's a variable), but then you > can't use these macros. > > Am I missing anything? This is needed in some places: $ ag 'stringify\(DEFAULT_CLUSTER_SIZE\)' block/parallels.c 99: .def_value_str = stringify(DEFAULT_CLUSTER_SIZE), block/vdi.c 988: .def_value_str = stringify(DEFAULT_CLUSTER_SIZE) block/qcow2.c 4726: .def_value_str = stringify(DEFAULT_CLUSTER_SIZE) The latter causes failure in test case 137 if defined as (64 * KiB). Of course the values in block/parallels.h and block/vdi.c will need to be changed as well, I'll do it in a separate patch. Besides resolving the cases with the necessity to stringify, It also creates nice shortcuts for all feasible power-of-two sizes, which are very common. Leonid. > > Berto >
diff --git a/include/qemu/units.h b/include/qemu/units.h index 692db3fbb2..68a7758650 100644 --- a/include/qemu/units.h +++ b/include/qemu/units.h @@ -17,4 +17,59 @@ #define PiB (INT64_C(1) << 50) #define EiB (INT64_C(1) << 60) +#define S_1KiB 1024 +#define S_2KiB 2048 +#define S_4KiB 4096 +#define S_8KiB 8192 +#define S_16KiB 16384 +#define S_32KiB 32768 +#define S_64KiB 65536 +#define S_128KiB 131072 +#define S_256KiB 262144 +#define S_512KiB 524288 +#define S_1MiB 1048576 +#define S_2MiB 2097152 +#define S_4MiB 4194304 +#define S_8MiB 8388608 +#define S_16MiB 16777216 +#define S_32MiB 33554432 +#define S_64MiB 67108864 +#define S_128MiB 134217728 +#define S_256MiB 268435456 +#define S_512MiB 536870912 +#define S_1GiB 1073741824 +#define S_2GiB 2147483648 +#define S_4GiB 4294967296 +#define S_8GiB 8589934592 +#define S_16GiB 17179869184 +#define S_32GiB 34359738368 +#define S_64GiB 68719476736 +#define S_128GiB 137438953472 +#define S_256GiB 274877906944 +#define S_512GiB 549755813888 +#define S_1TiB 1099511627776 +#define S_2TiB 2199023255552 +#define S_4TiB 4398046511104 +#define S_8TiB 8796093022208 +#define S_16TiB 17592186044416 +#define S_32TiB 35184372088832 +#define S_64TiB 70368744177664 +#define S_128TiB 140737488355328 +#define S_256TiB 281474976710656 +#define S_512TiB 562949953421312 +#define S_1PiB 1125899906842624 +#define S_2PiB 2251799813685248 +#define S_4PiB 4503599627370496 +#define S_8PiB 9007199254740992 +#define S_16PiB 18014398509481984 +#define S_32PiB 36028797018963968 +#define S_64PiB 72057594037927936 +#define S_128PiB 144115188075855872 +#define S_256PiB 288230376151711744 +#define S_512PiB 576460752303423488 +#define S_1EiB 1152921504606846976 +#define S_2EiB 2305843009213693952 +#define S_4EiB 4611686018427387904 +#define S_8EiB 9223372036854775808 + #endif
Adding a lookup table for the powers of two, with the appropriate size prefixes. This is needed when a size has to be stringified, in which case something like '(1 * KiB)' would become a literal '(1 * (1L << 10))' string. Powers of two are used very often for sizes, so such a table will also make it easier and more intuitive to write them. This table is generatred using the following AWK script: BEGIN { suffix="KMGTPE"; for(i=10; i<64; i++) { val=2**i; s=substr(suffix, int(i/10), 1); n=2**(i%10); pad=21-int(log(n)/log(10)); printf("#define S_%d%siB %*d\n", n, s, pad, val); } } Signed-off-by: Leonid Bloch <lbloch@janustech.com> --- include/qemu/units.h | 55 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+)