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    SubjectRe: [patch 0/2] x86, UV: fixups for configurations with a large number of nodes.
    On Fri, Oct 16, 2009 at 08:34:05AM +0200, Ingo Molnar wrote:
    >
    > * Robin Holt <holt@sgi.com> wrote:
    >
    > > We need the __uv_hub_info structure to contain the correct values for
    > > n_val, gpa_mask, and lowmem_remap_*. The first patch in the series
    > > accomplishes this. Could this be included in the stable tree as well.
    > > Without this patch, booting a large configuration hits a problem where
    > > the upper bits of the gnode affect the pnode and the bau will not
    > > operate.
    >
    > i've applied this one.

    Thank you for applying this one.

    > > The second patch cleans up the broadcast assist unit code a small bit.
    >
    > Seems to be more than just a 'cleanup'. It changes:

    I am going to rearrange a bit:

    > + return gpa >> uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1);
    >
    > note that >> has higher priority than bitwise & - is that intended? I
    > think the intention was:
    >
    > + return gpa >> (uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1));

    The intention was (gpa >> m_val) & (n_mask); I love the clarity of
    making it an explicitly stated mask. Much more readable.

    >
    > uv_nshift = uv_hub_info->m_val;
    >
    > to (in essence):
    >
    > uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1)
    >
    > which is not the same. Furthermore, the new inline is:

    You have an excellent point there. That was a bug as well. That may
    explain a few of our currently unexplained bau hangs. The value is
    supposed to be a pnode instead of the current gnode.

    Robin

    ---

    Create an inline function to extract the pnode from a global physical
    address and then convert the broadcast assist unit to use the newly
    created uv_gpa_to_pnode function.

    To: Ingo Molnar <mingo@elte.hu>
    To: tglx@linutronix.de
    Signed-off-by: Robin Holt <holt@sgi.com>
    Acked-by: Cliff Whickman <cpw@sgi.com>
    Cc: linux-mm@kvack.org
    Cc: linux-kernel@vger.kernel.org

    ---
    arch/x86/include/asm/uv/uv_hub.h | 16 +++++++++++++++-
    arch/x86/kernel/tlb_uv.c | 7 ++-----
    2 files changed, 17 insertions(+), 6 deletions(-)
    Index: linux/arch/x86/include/asm/uv/uv_hub.h
    ===================================================================
    --- linux.orig/arch/x86/include/asm/uv/uv_hub.h 2009-10-16 06:02:23.000000000 -0500
    +++ linux/arch/x86/include/asm/uv/uv_hub.h 2009-10-16 06:07:52.000000000 -0500
    @@ -114,7 +114,7 @@
    /*
    * The largest possible NASID of a C or M brick (+ 2)
    */
    -#define UV_MAX_NASID_VALUE (UV_MAX_NUMALINK_NODES * 2)
    +#define UV_MAX_NASID_VALUE (UV_MAX_NUMALINK_BLADES * 2)

    struct uv_scir_s {
    struct timer_list timer;
    @@ -230,6 +230,20 @@ static inline unsigned long uv_gpa(void
    return uv_soc_phys_ram_to_gpa(__pa(v));
    }

    +/* gnode -> pnode */
    +static inline unsigned long uv_gpa_to_gnode(unsigned long gpa)
    +{
    + return gpa >> uv_hub_info->m_val;
    +}
    +
    +/* gpa -> pnode */
    +static inline int uv_gpa_to_pnode(unsigned long gpa)
    +{
    + unsigned long n_mask = (1UL << uv_hub_info->n_val) - 1;
    +
    + return uv_gpa_to_gnode(gpa) & n_mask;
    +}
    +
    /* pnode, offset --> socket virtual */
    static inline void *uv_pnode_offset_to_vaddr(int pnode, unsigned long offset)
    {
    Index: linux/arch/x86/kernel/tlb_uv.c
    ===================================================================
    --- linux.orig/arch/x86/kernel/tlb_uv.c 2009-10-16 06:02:27.000000000 -0500
    +++ linux/arch/x86/kernel/tlb_uv.c 2009-10-16 06:02:28.000000000 -0500
    @@ -23,8 +23,6 @@
    static struct bau_control **uv_bau_table_bases __read_mostly;
    static int uv_bau_retry_limit __read_mostly;

    -/* position of pnode (which is nasid>>1): */
    -static int uv_nshift __read_mostly;
    /* base pnode in this partition */
    static int uv_partition_base_pnode __read_mostly;

    @@ -723,7 +721,7 @@ uv_activation_descriptor_init(int node,
    BUG_ON(!adp);

    pa = uv_gpa(adp); /* need the real nasid*/
    - n = pa >> uv_nshift;
    + n = uv_gpa_to_pnode(pa);
    m = pa & uv_mmask;

    uv_write_global_mmr64(pnode, UVH_LB_BAU_SB_DESCRIPTOR_BASE,
    @@ -778,7 +776,7 @@ uv_payload_queue_init(int node, int pnod
    * need the pnode of where the memory was really allocated
    */
    pa = uv_gpa(pqp);
    - pn = pa >> uv_nshift;
    + pn = uv_gpa_to_pnode(pa);
    uv_write_global_mmr64(pnode,
    UVH_LB_BAU_INTD_PAYLOAD_QUEUE_FIRST,
    ((unsigned long)pn << UV_PAYLOADQ_PNODE_SHIFT) |
    @@ -843,7 +841,6 @@ static int __init uv_bau_init(void)
    GFP_KERNEL, cpu_to_node(cur_cpu));

    uv_bau_retry_limit = 1;
    - uv_nshift = uv_hub_info->m_val;
    uv_mmask = (1UL << uv_hub_info->m_val) - 1;
    nblades = uv_num_possible_blades();


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