On Mon, Mar 06, 2006 at 02:59:29PM +0000, Thiemo Seufer wrote:
> Hello All,
>
> this patch vastly improves TLB performance on MIPS, and probably also
> on other architectures. I measured a Linux boot-shutdown cycle,
> including userland init.
Quoting the whole message since this is from March...
I don't remember seeing any followup discussion of this patch, but I
may have missed it. Thiemo's definitely right about "vastly". Is this
patch appropriate, or would anyone care to suggest a more
sophisticated data structure to avoid the full cache invalidate?
>
> With minimal jump cache invalidation:
>
> real 11m43.429s
> user 9m51.975s
> sys 0m1.375s
>
> 64.19 1476.81 1476.81 20551904 0.00 0.00 tlb_flush_page
> 6.72 1631.36 154.55 184346 0.00 0.00 cpu_mips_exec
> 4.35 1731.46 100.10 3550500 0.00 0.00 dyngen_code
> 3.66 1815.77 84.31 90897893 0.00 0.00 decode_opc
> 2.89 1882.21 66.44 11170487 0.00 0.00
> gen_intermediate_code_internal
> 1.72 1921.80 39.59 29919267 0.00 0.00 map_address
> 1.52 1956.66 34.86 7619987 0.00 0.00 tb_find_pc
> 0.96 1978.85 22.19 26361969 0.00 0.00 tlb_set_page_exec
> 0.96 2000.84 21.99 __ldl_mmu
> 0.90 2021.59 20.75 27279747 0.00 0.00 gen_arith_imm
>
>
> With global jump cache kill:
>
> real 6m19.811s
> user 4m23.650s
> sys 0m0.617s
>
> 21.67 188.78 188.78 146571 0.00 0.00 cpu_mips_exec
> 11.37 287.88 99.10 3393051 0.00 0.00 dyngen_code
> 9.59 371.45 83.57 89839869 0.00 0.00 decode_opc
> 7.68 438.33 66.88 10989930 0.00 0.00
> gen_intermediate_code_internal
> 4.24 475.26 36.93 30124659 0.00 0.00 map_address
> 3.80 508.33 33.07 7596879 0.00 0.00 tb_find_pc
> 2.74 532.22 23.89 27781692 0.00 0.00 tlb_set_page_exec
> 2.62 555.02 22.80 39891573 0.00 0.00
> cpu_mips_handle_mmu_fault
> 2.55 577.25 22.23 __ldl_mmu
> 2.30 597.26 20.01 26968709 0.00 0.00 gen_arith_imm
>
>
> Thiemo
>
>
> Index: qemu-work/exec.c
> ===================================================================
> --- qemu-work.orig/exec.c 2006-03-06 01:30:09.000000000 +0000
> +++ qemu-work/exec.c 2006-03-06 01:30:28.000000000 +0000
> @@ -1247,7 +1247,6 @@
> void tlb_flush_page(CPUState *env, target_ulong addr)
> {
> int i;
> - TranslationBlock *tb;
>
> #if defined(DEBUG_TLB)
> printf("tlb_flush_page: " TARGET_FMT_lx "\n", addr);
> @@ -1261,14 +1260,10 @@
> tlb_flush_entry(&env->tlb_table[0][i], addr);
> tlb_flush_entry(&env->tlb_table[1][i], addr);
>
> - for(i = 0; i < TB_JMP_CACHE_SIZE; i++) {
> - tb = env->tb_jmp_cache[i];
> - if (tb &&
> - ((tb->pc & TARGET_PAGE_MASK) == addr ||
> - ((tb->pc + tb->size - 1) & TARGET_PAGE_MASK) == addr)) {
> - env->tb_jmp_cache[i] = NULL;
> - }
> - }
> + /* We throw away the jump cache altogether. This is cheaper than
> + trying to be smart by invalidating only the entries in the
> + affected address range. */
> + memset (env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
>
> #if !defined(CONFIG_SOFTMMU)
> if (addr < MMAP_AREA_END)
>
>
> _______________________________________________
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>
--
Daniel Jacobowitz
CodeSourcery
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