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authorEric Dumazet <dada1@cosmosbay.com>2006-12-06 20:38:45 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:41 -0800
commitd18de5a2721f84ffd6a5d637915746ed47becc1c (patch)
tree85fa93f5a2003746792931463ed41b7a19cc8632 /sound
parent1c69d921ed9cc6593ad4f60c0f9951cb0d62b0b4 (diff)
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[PATCH] don't insert pipe dentries into dentry_hashtable.
We currently insert pipe dentries into the global dentry hashtable. This is suboptimal because there is currently no way these entries can be used for a lookup(). (/proc/xxx/fd/xxx uses a different mechanism). Inserting them in dentry hashtable slows dcache lookups. To let __dpath() still work correctly (ie not adding a " (deleted)") after dentry name, we do : - Right after d_alloc(), pretend they are hashed by clearing the DCACHE_UNHASHED bit. - Call d_instantiate() instead of d_add() : dentry is not inserted in hash table. __dpath() & friends work as intended during dentry lifetime. - At dismantle time, once dput() must clear the dentry, setting again DCACHE_UNHASHED bit inside the custom d_delete() function provided by pipe code, so that dput() can just kill_it. This patch, combined with (avoid RCU for never hashed dentries) reduced time of { pipe(p); close(p[0]); close(p[1]);} on my UP machine (1.6GHz Pentium-M) from 3.23 us to 2.86 us (But this patch does not depend on other patches, only bench results) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Acked-by: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'sound')
0 files changed, 0 insertions, 0 deletions
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