Messages in this thread | | | From | OGAWA Hirofumi <> | Subject | Re: [PATCH] fs/fat: calculate checksum in a loop instead of directly calculating | Date | Tue, 24 Feb 2015 11:42:39 +0900 |
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Heinrich Schuchardt <xypron.glpk@gmx.de> writes:
> You have to put > __attribute__((optimize("unroll-loops"))) > here to unroll the loop inside the function: > > > static __attribute__ ((noinline)) > __attribute__((optimize("unroll-loops"))) > int test(unsigned char *name) > > $ time ./c.inline aaaaaaaaaaa > 14 > > real 0m0.743s > user 0m0.740s > sys 0m0.000s > > Without __attribute__((optimize("unroll-loops"))) : > $ time ./c.loop aaaaaaaaaaa > 14 > > real 0m1.482s > user 0m1.472s > sys 0m0.004s > > With __attribute__((optimize("unroll-loops"))) : > > $ time ./c.loop aaaaaaaaaaa > 14 > > real 0m0.742s > user 0m0.740s > sys 0m0.000s
This attribute has to be added to the caller, not fat_checksum()? I.e., we has to add it to all callers of fat_checksum()?
Well, this is interesting gcc optimize option though, maybe not worth to introduce this to kernel only for fatfs.
Thanks. -- OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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