Date: Thu, 15 Nov 2012 12:25:21 -0600 From: Alan Cox <alc@rice.edu> To: mips@freebsd.org Cc: "Jayachandran C." <jchandra@freebsd.org> Subject: ZERO_REGION_SIZE Message-ID: <50A53391.4080909@rice.edu>
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Given the possibility of L1 cache aliasing on some (many?) MIPS processors, I think that you, i.e., MIPS users, should evaluate the performance effects of the following change: Index: mips/include/vmparam.h =================================================================== --- mips/include/vmparam.h (revision 243091) +++ mips/include/vmparam.h (working copy) @@ -190,6 +190,6 @@ */ #define VM_NFREEORDER 9 -#define ZERO_REGION_SIZE (64 * 1024) /* 64KB */ +#define ZERO_REGION_SIZE 4096 #endif /* !_MACHINE_VMPARAM_H_ */ You can quantify the impact with a simple test like: dd if=/dev/zero of=/dev/null bs=<64 or 128>k count=<something non-trivial> If possible, please use a kernel without WITNESS or INVARIANTS. Alan P.S. I would also be curious how setting this to 8192 would perform.
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