David Gibson <d...@au1.ibm.com> writes:
> On Mon, Apr 29, 2013 at 01:21:50AM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>>
>> Hugepage invalidate involves invalidating multiple hpte entries.
>> Optimize the operation using H_BULK_REMOVE on lpar platforms.
>> On native, reduce the number of tlb flush.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
>
> Since this is purely an optimization, have you tried reproducing the
> bugs you're chasing with this patch not included?
That was due to not handling thp split while walking page table. I have
that fixed. Will post the next version soon.
>
>> ---
>> arch/powerpc/include/asm/machdep.h | 3 +
>> arch/powerpc/mm/hash_native_64.c | 78 +++++++++++++++++++++
>> arch/powerpc/mm/pgtable_64.c | 13 +++-
>> arch/powerpc/platforms/pseries/lpar.c | 126
>> ++++++++++++++++++++++++++++++++--
>> 4 files changed, 210 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/machdep.h
>> b/arch/powerpc/include/asm/machdep.h
>> index 3f3f691..5d1e7d2 100644
>> --- a/arch/powerpc/include/asm/machdep.h
>> +++ b/arch/powerpc/include/asm/machdep.h
>> @@ -56,6 +56,9 @@ struct machdep_calls {
.....
>>
>> +/*
>> + * Limit iterations holding pSeries_lpar_tlbie_lock to 3. We also need
>> + * to make sure that we avoid bouncing the hypervisor tlbie lock.
>> + */
>> +#define PPC64_HUGE_HPTE_BATCH 12
>> +
>> +static void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
>> + unsigned long *vpn, int count,
>> + int psize, int ssize)
>> +{
>> + unsigned long param[9];
>
> [9]? I only see 8 elements being used.
cut paste error from pSeries_lpar_flush_hash_range
>
>> + int i = 0, pix = 0, rc;
>> + unsigned long flags = 0;
>> + int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
>> +
>> + if (lock_tlbie)
>> + spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
>
> Why are these hash operations being called with the tlbie lock held?
if the firmware doesn't support lockless TLBIE, we need to do locking
at the guest side. pSeries_lpar_flush_hash_range does that.
>
>> +
>> + for (i = 0; i < count; i++) {
>> +
>> + if (!firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
>> + pSeries_lpar_hpte_invalidate(slot[i], vpn[i], psize,
>> + ssize, 0);
>
> Couldn't you set the ppc_md hook based on the firmware request to
> avoid this test in the inner loop? I don't see any tlbie operations
> at all.
didn't get that.
>
>> + } else {
>> + param[pix] = HBR_REQUEST | HBR_AVPN | slot[i];
>> + param[pix+1] = hpte_encode_avpn(vpn[i], psize, ssize);
>> + pix += 2;
>> + if (pix == 8) {
>> + rc = plpar_hcall9(H_BULK_REMOVE, param,
>> + param[0], param[1], param[2],
>> + param[3], param[4], param[5],
>> + param[6], param[7]);
>> + BUG_ON(rc != H_SUCCESS);
>> + pix = 0;
>> + }
>> + }
>> + }
>> + if (pix) {
>> + param[pix] = HBR_END;
>> + rc = plpar_hcall9(H_BULK_REMOVE, param, param[0], param[1],
>> + param[2], param[3], param[4], param[5],
>> + param[6], param[7]);
>> + BUG_ON(rc != H_SUCCESS);
>> + }
>> +
>> + if (lock_tlbie)
>> + spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
>> +}
>> +
>> +static void pSeries_lpar_hugepage_invalidate(struct mm_struct *mm,
>> + unsigned char *hpte_slot_array,
>> + unsigned long addr, int psize)
>> +{
>> + int ssize = 0, i, index = 0;
>> + unsigned long s_addr = addr;
>> + unsigned int max_hpte_count, valid;
>> + unsigned long vpn_array[PPC64_HUGE_HPTE_BATCH];
>> + unsigned long slot_array[PPC64_HUGE_HPTE_BATCH];
>> + unsigned long shift, hidx, vpn = 0, vsid, hash, slot;
>> +
>> + shift = mmu_psize_defs[psize].shift;
>> + max_hpte_count = HUGE_PAGE_SIZE >> shift;
>> +
>> + for (i = 0; i < max_hpte_count; i++) {
>> + /*
>> + * 8 bits per each hpte entries
>> + * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
>> + */
>> + valid = hpte_slot_array[i] & 0x1;
>> + if (!valid)
>> + continue;
>> + hidx = hpte_slot_array[i] >> 1;
>> +
>> + /* get the vpn */
>> + addr = s_addr + (i * (1ul << shift));
>> + if (!is_kernel_addr(addr)) {
>> + ssize = user_segment_size(addr);
>> + vsid = get_vsid(mm->context.id, addr, ssize);
>> + WARN_ON(vsid == 0);
>> + } else {
>> + vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
>> + ssize = mmu_kernel_ssize;
>> + }
>> +
>> + vpn = hpt_vpn(addr, vsid, ssize);
>> + hash = hpt_hash(vpn, shift, ssize);
>> + if (hidx & _PTEIDX_SECONDARY)
>> + hash = ~hash;
>> +
>> + slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
>> + slot += hidx & _PTEIDX_GROUP_IX;
>> +
>> + slot_array[index] = slot;
>> + vpn_array[index] = vpn;
>> + if (index == PPC64_HUGE_HPTE_BATCH - 1) {
>> + /*
>> + * Now do a bluk invalidate
>> + */
>> + __pSeries_lpar_hugepage_invalidate(slot_array,
>> + vpn_array,
>> +
>> PPC64_HUGE_HPTE_BATCH,
>> + psize, ssize);
>
> I don't really understand why you have one loop in this function, then
> another in the __ function.
?? if we didn't accumulate batch size number of entries, we won't call
the above. Hence we will have to do the bulk remove outside the if
loop.
>
>> + index = 0;
>> + } else
>> + index++;
>> + }
>> + if (index)
>> + __pSeries_lpar_hugepage_invalidate(slot_array, vpn_array,
>> + index, psize, ssize);
>> +}
>> +
>> static void pSeries_lpar_hpte_removebolted(unsigned long ea,
>> int psize, int ssize)
>> {
>> @@ -360,13 +478,6 @@ static void pSeries_lpar_hpte_removebolted(unsigned
>> long ea,
>> pSeries_lpar_hpte_invalidate(slot, vpn, psize, ssize, 0);
>> }
>>
>> -/* Flag bits for H_BULK_REMOVE */
>> -#define HBR_REQUEST 0x4000000000000000UL
>> -#define HBR_RESPONSE 0x8000000000000000UL
>> -#define HBR_END 0xc000000000000000UL
>> -#define HBR_AVPN 0x0200000000000000UL
>> -#define HBR_ANDCOND 0x0100000000000000UL
>> -
>> /*
>> * Take a spinlock around flushes to avoid bouncing the hypervisor tlbie
>> * lock.
>> @@ -452,6 +563,7 @@ void __init hpte_init_lpar(void)
>> ppc_md.hpte_removebolted = pSeries_lpar_hpte_removebolted;
>> ppc_md.flush_hash_range = pSeries_lpar_flush_hash_range;
>> ppc_md.hpte_clear_all = pSeries_lpar_hptab_clear;
>> + ppc_md.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;
>> }
>>
>> #ifdef CONFIG_PPC_SMLPAR
>
> --
-aneesh
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