From ce61cdc270a5e0dd18057bbf29bd3471abccbda8 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Thu, 15 Aug 2013 16:29:02 -0400 Subject: tile: make __write_once a synonym for __read_mostly This was really only useful for TILE64 when we mapped the kernel data with small pages. Now we use a huge page and we really don't want to map different parts of the kernel data in different ways. We retain the __write_once name in case we want to bring it back to life at some point in the future. Note that this change uncovered a latent bug where the "smp_topology" variable happened to always be aligned mod 8 so we could store two "int" values at once, but when we eliminated __write_once it ended up only aligned mod 4. Fix with an explicit annotation. Signed-off-by: Chris Metcalf --- arch/tile/include/asm/cache.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'arch/tile/include/asm/cache.h') diff --git a/arch/tile/include/asm/cache.h b/arch/tile/include/asm/cache.h index a9a529964e07..6160761d5f61 100644 --- a/arch/tile/include/asm/cache.h +++ b/arch/tile/include/asm/cache.h @@ -49,9 +49,16 @@ #define __read_mostly __attribute__((__section__(".data..read_mostly"))) /* - * Attribute for data that is kept read/write coherent until the end of - * initialization, then bumped to read/only incoherent for performance. + * Originally we used small TLB pages for kernel data and grouped some + * things together as "write once", enforcing the property at the end + * of initialization by making those pages read-only and non-coherent. + * This allowed better cache utilization since cache inclusion did not + * need to be maintained. However, to do this requires an extra TLB + * entry, which on balance is more of a performance hit than the + * non-coherence is a performance gain, so we now just make "read + * mostly" and "write once" be synonyms. We keep the attribute + * separate in case we change our minds at a future date. */ -#define __write_once __attribute__((__section__(".w1data"))) +#define __write_once __read_mostly #endif /* _ASM_TILE_CACHE_H */ -- cgit v1.2.3