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Date: Sat, 11 Jun 2016 18:16:15 -0700 From: Randy Dunlap <rdunlap@...radead.org> To: George Spelvin <linux@...encehorizons.net>, linux-kernel@...r.kernel.org Cc: mszeredi@...hat.com, npiggin@...il.com, paulmck@...ux.vnet.ibm.com, torvalds@...ux-foundation.org, viro@...iv.linux.org.uk Subject: Re: [PATCH] vfs: add simple direct-mapped dcache lookup front-end Hi, Just a small typo in Kconfig below.. On 06/11/16 16:51, George Spelvin wrote: > > fs/Kconfig | 28 ++++++++ > fs/dcache.c | 207 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 231 insertions(+), 4 deletions(-) > > diff --git a/fs/Kconfig b/fs/Kconfig > index b8fcb416..3b111b77 100644 > --- a/fs/Kconfig > +++ b/fs/Kconfig > @@ -8,6 +8,34 @@ menu "File systems" > config DCACHE_WORD_ACCESS > bool > > +config L1_DCACHE_BITS > + int "Dcache level-1 cache size (bits)" > + range 0 20 > + default 0 if !EXPERT > + default 0 if NUMA > + default 10 if BASE_SMALL > + default 13 > + help > + The Linus kernel maintains a large cache of "dentries" Linux > + (directory entries) for the performance-critical task of > + converting file names to inodes. This option enables a smaller > + direct-mapped "level-1 cache" in front of the main dcache. > + > + (This software "dcache" is quite different from the CPU's data > + cache, or "D-cache". Sorry for the confusingly similar names.) > + > + This option specifies the size of this cache, as a power of 2. > + For example, 13 means 2^13 = 8192 entries in the L1 dcache. > + Specify 0 to turn off the L1 dcache entirely. > + > + The cost of enabling this is one pointer per entry, plus a > + small amount of code. > + > + This is an experimental feature which hopes to speed up > + single-socket machines. On larger systems, the extra updates > + generated by the L1 dcache probably cause too much cache-line > + bouncing to be worth it. > + > if BLOCK > > source "fs/ext2/Kconfig" -- ~Randy
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