Re: [PATCH v3 2/2] x86: Add support for the clwb instruction

From: H. Peter Anvin
Date: Wed Feb 11 2015 - 17:25:30 EST

On 01/27/2015 08:53 AM, Ross Zwisler wrote:
> Add support for the new clwb (cache line write back) instruction. This
> instruction was announced in the document "Intel Architecture
> Instruction Set Extensions Programming Reference" with reference number
> 319433-022.
> The clwb instruction is used to write back the contents of dirtied cache
> lines to memory without evicting the cache lines from the processor's
> cache hierarchy. This should be used in favor of clflushopt or clflush
> in cases where you require the cache line to be written to memory but
> plan to access the data again in the near future.
> One of the main use cases for this is with persistent memory where clwb
> can be used with pcommit to ensure that data has been accepted to memory
> and is durable on the DIMM.

Acked-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>

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