From: Dan Magenheimer Date: Mon, 23 Jan 2012 21:52:20 +0000 (-0500) Subject: zcache: Set SWIZ_BITS to 8 to reduce tmem bucket lock contention. X-Git-Tag: v3.3-rc4~40^2~17 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8b4553457e78bcff90f70a31212a40a8fd4f0db;p=pandora-kernel.git zcache: Set SWIZ_BITS to 8 to reduce tmem bucket lock contention. SWIZ_BITS > 8 results in a much larger number of "tmem_obj" allocations, likely one per page-placed-in-frontswap. The tmem_obj is not huge (roughly 100 bytes), but it is large enough to add a not-insignificant memory overhead to zcache. The SWIZ_BITS=8 will get roughly the same lock contention without the space wastage. The effect of SWIZ_BITS can be thought of as "2^SWIZ_BITS is the number of unique oids that be generated" (This concept is limited to frontswap's use of tmem). Acked-by: Seth Jennings Signed-off-by: Konrad Rzeszutek Wilk Cc: stable Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed