Re: Inefficient TLB flushing

[Andrew Morton <akpm@osdl.org>]

David Mosberger <davidm@napali.hpl.hp.com> wrote:
>
>   Jack> Here is the patch that I am currently testing:
> 
>   Jack> --- /usr/tmp/TmpDir.19957-0/linux/mm/memory.c_1.79	Wed Nov 12 13:56:25 2003
>   Jack> +++ linux/mm/memory.c	Wed Nov 12 12:57:25 2003
>   Jack> @@ -574,9 +574,10 @@
>   Jack>  			if ((long)zap_bytes > 0)
>   Jack>  				continue;
>   Jack>  			if (need_resched()) {
>   Jack> +				int fullmm = (*tlbp)->fullmm;
>   Jack>  				tlb_finish_mmu(*tlbp, tlb_start, start);
>   Jack>  				cond_resched_lock(&mm->page_table_lock);
>   Jack> -				*tlbp = tlb_gather_mmu(mm, 0);
>   Jack> +				*tlbp = tlb_gather_mmu(mm, fullmm);
>   Jack>  				tlb_start_valid = 0;
>   Jack>  			}
>   Jack>  			zap_bytes = ZAP_BLOCK_SIZE;
> 
> I think the patch will work fine, but it's not very clean, because it
> bypasses the TLB-flush API and directly accesses
> implementation-specific internals.  Perhaps it would be better to pass
> a "fullmm" flag to unmap_vmas().  Andrew?

Either that, or add a new interface function

	int mmu_gather_is_full_mm(mmu_gather *tlb);

and use it...