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Date: Fri, 18 Jul 2014 14:23:04 -0700 From: Tony Luck <tony.luck@...il.com> To: Borislav Petkov <bp@...en8.de> Cc: Havard Skinnemoen <hskinnemoen@...gle.com>, Linux Kernel <linux-kernel@...r.kernel.org>, Ewout van Bekkum <ewout@...gle.com> Subject: Re: [PATCH 4/6] x86-mce: Add spinlocks to prevent duplicated MCP and CMCI reports. On Thu, Jul 17, 2014 at 3:50 AM, Borislav Petkov <bp@...en8.de> wrote: > Well, maybe it is about time we tracked shared banks. For cpus that support CMCI and the MCi_CTL2 registers we do track sharing. Only one cpu gets to be the "owner" of a bank that supports CMCI (the first one to find it and set bit 30 in the CTL2 register). The test_bit() at the top of the loop in machine_check_poll() makes sure only the owner of a bank actually looks at it. for (i = 0; i < mca_cfg.banks; i++) { if (!mce_banks[i].ctl || !test_bit(i, *b)) continue; If we don't have CMCI, then we don't have the CTL2 registers, and so have no way to find out which banks are shared. > We can evaluate later if the IRQs disabling is too heavy after all. I'd be surprised if it was a problem in practice. If we have CMCI, then we limit the banks that we look at (and if we see a high rate of interrupts, then we turn off interrupts an poll). If we don't have CMCI, then we are polling at a pretty low rate (current code adjusts the rate higher if we are finding errors to log, but we don't let that rate rise forever ... cap is ~ 1HZ). -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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