Re: [Crash-utility] [PATCH] diskdump: Optimize the boot time

-----Original Message----- > 1.) The vmcore file maybe very big. > > For example, I have a vmcore file which is over 23G, > and the panic kernel had 767.6G memory, > its max_sect_len is 4468736. > > Current code costs too much time to do the following loop: > .............................................. > for (i = 1; i < max_sect_len + 1; i++) { > dd->valid_pages[i] = dd->valid_pages[i - 1]; > for (j = 0; j < BITMAP_SECT_LEN; j++, pfn++) > if (page_is_dumpable(pfn)) > dd->valid_pages[i]++; > .............................................. > > For my case, it costs about 56 seconds to finish the > big loop. > > This patch moves the hweightXX macros to defs.h, > and uses hweight64 to optimize the loop. > > For my vmcore, the loop only costs about one second now. > > 2.) Tests result: > # cat ./commands.txt > quit > > Before: > > #echo 3 > /proc/sys/vm/drop_caches; > #time ./crash -i ./commands.txt /root/t/vmlinux /root/t/vmcore > /dev/null 2>&1 > ............................ > real 1m54.259s > user 1m12.494s > sys 0m3.857s > ............................ > > After this patch: > > #echo 3 > /proc/sys/vm/drop_caches; > #time ./crash -i ./commands.txt /root/t/vmlinux /root/t/vmcore > /dev/null 2>&1 > ............................ > real 0m55.217s > user 0m15.114s > sys 0m3.560s > ............................ Thank you for the improvement! as far as I tested on x86_64 it did not give such a big gain, but looking at the user time, it will do on arm64. Lianbo, can you reproduce on arm64? with a 192GB x86_64 dumpfile, slightly improved: $ time echo quit | ./crash vmlinux dump >/dev/null real 0m5.632s

user 0m5.545s sys 0m0.185s $ time echo quit | ./crash vmlinux dump >/dev/null real 0m5.547s user 0m5.477s sys 0m0.170s > > Signed-off-by: Huang Shijie <shijie(a)os.amperecomputing.com&gt; > --- > defs.h | 20 ++++++++++++++++++++ > diskdump.c | 12 +++++++++--- > sbitmap.c | 19 ------------------- > 3 files changed, 29 insertions(+), 22 deletions(-) > > diff --git a/defs.h b/defs.h > index 81ac049..1e8360d 100644 > --- a/defs.h > +++ b/defs.h > @@ -4531,6 +4531,26 @@ struct machine_specific { > #define NUM_IN_BITMAP(bitmap, x) (bitmap[(x)/BITS_PER_LONG] & NUM_TO_BIT(x)) > #define SET_BIT(bitmap, x) (bitmap[(x)/BITS_PER_LONG] |= NUM_TO_BIT(x)) > > +static inline unsigned int __const_hweight8(unsigned long w) > +{ > + return > + (!!((w) & (1ULL << 0))) + > + (!!((w) & (1ULL << 1))) + > + (!!((w) & (1ULL << 2))) + > + (!!((w) & (1ULL << 3))) + > + (!!((w) & (1ULL << 4))) + > + (!!((w) & (1ULL << 5))) + > + (!!((w) & (1ULL << 6))) + > + (!!((w) & (1ULL << 7))); > +} > + > +#define __const_hweight16(w) (__const_hweight8(w) + __const_hweight8((w) >> 8)) > +#define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16)) > +#define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) > + > +#define hweight32(w) __const_hweight32(w) > +#define hweight64(w) __const_hweight64(w) > + > /* > * precision lengths for fprintf > */ > diff --git a/diskdump.c b/diskdump.c > index d567427..d30db9d 100644 > --- a/diskdump.c > +++ b/diskdump.c > @@ -547,6 +547,7 @@ read_dump_header(char *file) > ulong pfn; > int i, j, max_sect_len; > int is_split = 0; > + u64 tmp, *bitmap; $ make warn ... cc -c -g -DX86_64 -DLZO -DSNAPPY -DZSTD -DGDB_10_2 diskdump.c -Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security diskdump.c: In function ‘read_dump_header’: diskdump.c:550:2: error: unknown type name ‘u64’ u64 tmp, *bitmap; ^~~ diskdump.c:905:12: error: ‘u64’ undeclared (first use in this function); did you mean ‘a64l’? bitmap = (u64 *)dd->dumpable_bitmap; ^~~ a64l It looks like u64 is defined only on arm and arm64, please use ulonglong commonly used in crash.