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blk-iocost: avoid 64-bit division in ioc_timer_fn
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The behavior of 'enum' types has changed in gcc-13, so now the
UNBUSY_THR_PCT constant is interpreted as a 64-bit number because
it is defined as part of the same enum definition as some other
constants that do not fit within a 32-bit integer. This in turn
leads to some inefficient code on 32-bit architectures as well
as a link error:

arm-linux-gnueabi/bin/arm-linux-gnueabi-ld: block/blk-iocost.o: in function `ioc_timer_fn':
blk-iocost.c:(.text+0x68e8): undefined reference to `__aeabi_uldivmod'
arm-linux-gnueabi-ld: blk-iocost.c:(.text+0x6908): undefined reference to `__aeabi_uldivmod'

Split the enum definition to keep the 64-bit timing constants in
a separate enum type from those constants that can clearly fit
within a smaller type.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230118080706.3303186-1-arnd@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Arnd Bergmann authored and Jens Axboe committed Jan 29, 2023
1 parent 464544f commit 5f2779d
Showing 1 changed file with 5 additions and 3 deletions.
8 changes: 5 additions & 3 deletions block/blk-iocost.c
Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,11 @@ enum {
VRATE_MIN = VTIME_PER_USEC * VRATE_MIN_PPM / MILLION,
VRATE_CLAMP_ADJ_PCT = 4,

/* switch iff the conditions are met for longer than this */
AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC,
};

enum {
/* if IOs end up waiting for requests, issue less */
RQ_WAIT_BUSY_PCT = 5,

Expand Down Expand Up @@ -296,9 +301,6 @@ enum {
/* don't let cmds which take a very long time pin lagging for too long */
MAX_LAGGING_PERIODS = 10,

/* switch iff the conditions are met for longer than this */
AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC,

/*
* Count IO size in 4k pages. The 12bit shift helps keeping
* size-proportional components of cost calculation in closer
Expand Down

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