On 11/4/2020 3:59 PM, Vijayanand Jitta wrote: > > > 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 > Awaiting for comments from Andrew and others. Thanks, Vijay -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
