On 11/4/2020 4:57 AM, Minchan Kim wrote: > 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. > > This idea looks fine to me. Andrew and others would like to hear your comments as well on this before implementing. Thanks, Vijay -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
