Re: [PATCH 0/3] TLB flush multiple pages per IPI v5

From	Dave Hansen <dave.hansen@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/3] TLB flush multiple pages per IPI v5
Date	2015-06-08 20:30 +0200
Message-ID	<pz9Y6-6UC-21@gated-at.bofh.it> (permalink)
References	<pz4OL-7rP-15@gated-at.bofh.it> <pz9lo-5RJ-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 06/08/2015 10:45 AM, Ingo Molnar wrote:
> As per my measurements the __flush_tlb_single() primitive (which you use in patch
> #2) is very expensive on most Intel and AMD CPUs. It barely makes sense for a 2
> pages and gets exponentially worse. It's probably done in microcode and its 
> performance is horrible.

I discussed this a bit in commit a5102476a2.  I'd be curious what
numbers you came up with.

But, don't we have to take in to account the cost of refilling the TLB
in addition to the cost of emptying it?  The TLB size is historically
increasing on a per-core basis, so isn't this refill cost only going to
get worse?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH 0/3] TLB flush multiple pages per IPI v5 Dave Hansen <dave.hansen@intel.com> - 2015-06-08 20:30 +0200
  Re: [PATCH 0/3] TLB flush multiple pages per IPI v5 Ingo Molnar <mingo@kernel.org> - 2015-06-08 22:00 +0200
    Re: [PATCH 0/3] TLB flush multiple pages per IPI v5 Ingo Molnar <mingo@kernel.org> - 2015-06-08 22:10 +0200

csiph-web