Sorry if this mail corrupts the mail thread or had heavy mangling since I lost this mail from my mailbox so I am sending this mail by web gmail. On Thu, Oct 22, 2020 at 10:18 AM <vjitta@xxxxxxxxxxxxxx> wrote: > > From: Yogesh Lal <ylal@xxxxxxxxxxxxxx> > > Use STACK_HASH_ORDER_SHIFT to configure STACK_HASH_SIZE. > > Aim is to have configurable value for STACK_HASH_SIZE, > so depend on use case one can configure it. > > One example is of Page Owner, default value of > STACK_HASH_SIZE lead stack depot to consume 8MB of static memory. > Making it configurable and use lower value helps to enable features like > CONFIG_PAGE_OWNER without any significant overhead. > > Signed-off-by: Yogesh Lal <ylal@xxxxxxxxxxxxxx> > Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> > Signed-off-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> > --- > lib/Kconfig | 9 +++++++++ > lib/stackdepot.c | 3 +-- > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/lib/Kconfig b/lib/Kconfig > index 18d76b6..b3f8259 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -651,6 +651,15 @@ config STACKDEPOT > bool > select STACKTRACE > > +config STACK_HASH_ORDER_SHIFT > + int "stack depot hash size (12 => 4KB, 20 => 1024KB)" > + range 12 20 > + default 20 > + depends on STACKDEPOT > + help > + Select the hash size as a power of 2 for the stackdepot hash table. > + Choose a lower value to reduce the memory impact. > + > config SBITMAP > bool > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index 2caffc6..413c20b 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -142,8 +142,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, > return stack; > } > > -#define STACK_HASH_ORDER 20 > -#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER) > +#define STACK_HASH_SIZE (1L << CONFIG_STACK_HASH_ORDER_SHIFT) > #define STACK_HASH_MASK (STACK_HASH_SIZE - 1) > #define STACK_HASH_SEED 0x9747b28c > > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation > 2.7.4 > 1. When we don't use page_owner, we don't want to waste any memory for stackdepot hash array. 2. When we use page_owner, we want to have reasonable stackdeport hash array With this configuration, it couldn't meet since we always need to reserve a reasonable size for the array. Can't we make the hash size as a kernel parameter? With it, we could use it like this. 1. page_owner=off, stackdepot_stack_hash=0 -> no more wasted memory when we don't use page_owner 2. page_owner=on, stackdepot_stack_hash=8M -> reasonable hash size when we use page_owner. -- Kind regards, Minchan Kim
