Re: [Crash-utility] [PATCH v2] diskdump: Optimize the boot time

Hi, Shijie Thank you for the update. On Wed, Mar 30, 2022 at 8:00 PM <crash-utility-request(a)redhat.com&gt; wrote: > Date: Wed, 30 Mar 2022 19:03:23 +0000 > From: Huang Shijie <shijie(a)os.amperecomputing.com&gt; > To: k-hagio-ab(a)nec.com, lijiang(a)redhat.com > Cc: patches(a)amperecomputing.com, zwang(a)amperecomputing.com, > darren(a)os.amperecomputing.com, crash-utility(a)redhat.com, Huang > Shijie > <shijie(a)os.amperecomputing.com&gt; > Subject: [Crash-utility] [PATCH v2] diskdump: Optimize the boot time > Message-ID: <20220330190323.2420144-1-shijie(a)os.amperecomputing.com&gt; > Content-Type: text/plain > > 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 > ............................ > > Signed-off-by: Huang Shijie <shijie(a)os.amperecomputing.com&gt; > --- > v1 --> v2: > 1.) change u64 to ulonglong. > 2.) compile this patch in x86_64. > > --- > 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) > + > No need to move the above code from sbitmap.c to defs.h, a simple way is to implement a new function in sbitmap.c and add its definition in defs.h, that will be easy to call it in diskdump.c. For example: diff --git a/defs.h b/defs.h index 81ac0498dac7..0c5115e71f1c 100644 --- a/defs.h +++ b/defs.h @@ -5894,6 +5894,7 @@ typedef bool (*sbitmap_for_each_fn)(unsigned int idx, void *p); void sbitmap_for_each_set(const struct sbitmap_context *sc, sbitmap_for_each_fn fn, void *data); void sbitmap_context_load(ulong addr, struct sbitmap_context *sc); +unsigned long get_hweight64(unsigned long w); /* sbitmap_queue helpers */ typedef bool (*sbitmapq_for_each_fn)(unsigned int idx, ulong addr, void *p); diff --git a/sbitmap.c b/sbitmap.c index 286259f71d64..628cc00c0b6b 100644 --- a/sbitmap.c +++ b/sbitmap.c @@ -71,6 +71,11 @@ static inline unsigned int __const_hweight8(unsigned long w) #define BIT(nr) (1UL << (nr)) +unsigned long get_hweight64(unsigned long w) +{ + return hweight64(w); +} + static inline unsigned long min(unsigned long a, unsigned long b) { return (a < b) ? a : b; //diskdump.c ... dd->valid_pages[i] += get_hweight64(tmp); ... How about the above suggestions? Shijie and Kazu.