LispWorks User Guide and Reference Manual > 40 The SYSTEM Package

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set-spare-keeping-policy

Function
Summary

Controls the behavior of the system when a segment is emptied in 64-bit LispWorks.

Package

system

Signature

set-spare-keeping-policy gen-num policy => old-policy

Arguments

gen-num

An integer in the inclusive range [0,7].

policy

A generalized boolean.

Values

old-policy

A generalized boolean.

Description

The function set-spare-keeping-policy controls the behavior of the system when a segment is emptied in 64-bit LispWorks.

If policy is non-nil, then when a segment in generation gen-num is emptied by copying all the objects out from it, it may be kept as a spare segment to be used in the future. This increases the use of virtual memory, but reduces the number of calls to mmap and munmap . It may be useful in applications that allocate at a very high rate.

If timing an application reveals a lot (more than 5%) of time in the "System Time", and especially if this shows up in the GC times produced by extended-time, it may be useful to set the policy to non-nil in generation 1, 2 and maybe in generation 3.

The default policy is nil for all generations, meaning that empty segments are discarded.

The returned value old-policy is the previous policy for the generation gen-num .

Note: this function is implemented only in 64-bit LispWorks. It is not relevant to the Memory Management API in 32-bit implementations.

See also

extended-time


LispWorks User Guide and Reference Manual - 22 Dec 2009

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