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Re: [Qemu-devel] [RFC 6/7] [XXX] tcg: make TCGContext thread-local for s
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [RFC 6/7] [XXX] tcg: make TCGContext thread-local for softmmu |
Date: |
Fri, 30 Jun 2017 01:18:58 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 |
On 06/29/2017 01:28 PM, Emilio G. Cota wrote:
This will allow us to generate TCG code in parallel.
User-mode is kept out of this: contention due to concurrent translation
is more commonly found in full-system mode (e.g. booting a many-core guest).
XXX: For now, only convert arm/a64, since these are the only guests that
have proper MTTCG support.
Not true. TCG_GUEST_DEFAULT_MO suggests we have 4.
XXX: This is calling prologue_init once per vCPU, i.e. each TCGContext
gets a different prologue/epilogue (all of them with the same
contents though). Far from ideal, but for an experiment it
"should" work, right?
Um... sure. But surely there's a better way. Perhaps copying the main
thread's tcg_ctx? That'd be after prologue, and target globals are created.
That would avoid the need to make all the target cpu_* globals be thread-local,
for instance.
Of course, now that I think of it, this implies that my tcg patches to use
pointers instead of indicies is not the Way Forward...
/* Share the TCG temporaries common between 32 and 64 bit modes. */
-extern TCGv_env cpu_env;
-extern TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
-extern TCGv_i64 cpu_exclusive_addr;
-extern TCGv_i64 cpu_exclusive_val;
+extern TCG_THREAD TCGv_env cpu_env;
+extern TCG_THREAD TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
+extern TCG_THREAD TCGv_i64 cpu_exclusive_addr;
+extern TCG_THREAD TCGv_i64 cpu_exclusive_val;
It would be Really Good if we could avoid this in the end.
I see that it's the quickest way to test for now though.
@@ -887,7 +893,7 @@ typedef struct TCGOpDef {
#endif
} TCGOpDef;
-extern TCGOpDef tcg_op_defs[];
+extern TCG_THREAD TCGOpDef tcg_op_defs[];
Why? It's constant after startup.
r~