在x86-64上，是"movnti"或"movntdq".系统崩溃时的指令原子? [英] On x86-64, is the “movnti” or "movntdq" instruction atomic when system crash?

问题描述

使用像Intel optane DCPMM这样的永久性内存时，如果在执行movnt指令时系统崩溃(断电)，重启后是否有可能看到部分结果?

When using persistent memory like Intel optane DCPMM, is it possible to see partial result after reboot if system crash(power outage) in execution of movnt instruction?

针对:

• 4或8字节的 movnti ，x86可以保证原子用于其他目的吗?
• 16字节SSE movntdq / movntps 不能保证是原子的，但实际上可能在支持持久性内存的CPU上.
• 32字节AVX vmovntdq / vmovntps
• 64字节AVX512 vmovntdq / vmovntps 全线存储
• 额外的问题: MOVDIR64B 已保证64字节在支持它和DC-PM的未来CPU上写原子性.例如蓝宝石急流至强/老虎湖/特里蒙特.

• 4 or 8 byte movnti which x86 guarantees atomic for other purposes?
• 16-byte SSE movntdq / movntps which aren't guaranteed atomic but which in practice probably are on CPUs supporting persistent memory.
• 32-byte AVX vmovntdq / vmovntps
• 64-byte AVX512 vmovntdq / vmovntps full-line stores
• bonus question: MOVDIR64B which has guaranteed 64-byte write atomicity, on future CPUs that support it and DC-PM. e.g. Sapphire Rapids Xeon / Tiger Lake / Tremont.

movntpd 与 movntps 相同.

相关问题:

• 在x86-64上是"movnti"指令是原子的吗?是
• 系统崩溃时clflush或clflushopt是原子的吗?

推荐答案

x86在全局可观察性和持久性方面的原子性保证是相同的.这意味着以下操作始终是原子的:

Atomicity guarantees on x86 in global observability and persistency are the same. This means that the following operations are persistently atomic:

• 没有跨越8字节边界到任何有效内存类型的位置的存储uop，并且
• MOVDIR64B .

此外，以下操作始终是原子的:

In addition, the following operations are persistently atomic:

• 刷新缓存行( CLFLUSH 或 CLFLUSHOPT )，
• 缓存行写回( CLWB )和
• 非体系结构缓存行逐出.
• 英特尔处理器上的完整写合并缓冲区刷新.WCB的存在和大小以及冲洗的原因是特定于实现的.请参阅:将英特尔非临时性商店订购到相同的缓存行.

• A cache line flush (CLFLUSH or CLFLUSHOPT),
• A cache line writeback (CLWB), and
• A non-architectural cache line eviction.
• A full write-combining buffer flush on Intel processors. The presence and size of WCBs and the causes of flush are implementation-specific. See: Ordering of Intel non-temporal stores to the same cache line.

对于其他所有内容，包括64字节AVX512 vmovntdq / vmovntps 全线存储，都没有体系结构上的持久性原子保证.

There is no architectural persistent atomicity guarantee for everything else, including 64-byte AVX512 vmovntdq / vmovntps full-line stores.

这些保证适用于异步DRAM刷新(ADR)平台和增强型异步DRAM刷新(eADR)平台.(在eADR上，缓存层次结构位于持久性域中.请参阅:

These guarantees apply to Asynchronous DRAM Refresh (ADR) platforms and Enhanced Asynchronous DRAM Refresh (eADR) platforms. (On eADR, the cache hierarchy is in the persistence domain. See: Build Persistent Memory Applications with Reliability Availability and Serviceability.)

此答案基于我与Andy Rudoff(英特尔)的私人通信.

This answer is based on my private correspondence with Andy Rudoff (Intel).

这篇关于在x86-64上，是"movnti"或"movntdq".系统崩溃时的指令原子?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！