> -----Original Message----- > From: Len Brown [mailto:lenb@xxxxxxxxxx] > Sent: Tuesday, May 25, 2010 1:43 PM > To: Philip Langdale > Cc: Matthew Garrett; Jeff Garrett; Andi Kleen; Linux Kernel Mailing > List; linux-acpi@xxxxxxxxxxxxxxx; Yu, Luming; venki@xxxxxxxxxx > Subject: Re: acpi_idle: Very idle Core i7 machine never enters C3 > > > >> I am hopeful that the "right thing to do" is to not look at bm- > status > > >> and that perhaps there is a bug where we are looking at it > > >> "by mistake". > > > > > > https://patchwork.kernel.org/patch/58962/ - it seems to be a win. > > > > Indeed. This patch does solve the C6 problem. I'm not in a position > to > > speak about whether there's any undesirable I/O latency, but it > > passes the basic sanity check. > > > > I have filed https://bugzilla.kernel.org/show_bug.cgi?id=15886 with > > my acpi dump - assuming that's still useful. > > Luming's patch above basically deletes acpi_idle_bm_check() -- > the BM_STS check -- from the C3 path on all Intel SMP boxes. > This is effectively the same as my test patch > https://patchwork.kernel.org/patch/77370/ > that made acpi_idle_bm_check() do nothing. > > I'm told by the hardware guys that BM_STS is _not_ always > a NOP, and so we're not supposed to simply ignore it on C3 -- > though it should be extremely rare that we see it set. On some platforms like NHM-EX, I was told that it's a NOP, But I might be given wrong information at that time when I wrote that patch. IIRC, acpi spec just say it's optional.. Thanks, Luming -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
