diff options
| author | David Gibson <david@gibson.dropbear.id.au> | 2016-02-09 10:15:12 +1000 |
|---|---|---|
| committer | David Gibson <david@gibson.dropbear.id.au> | 2016-02-17 09:59:30 +1100 |
| commit | 8dfe8e7f4facef400ef1c220f29196ae5cfc526c (patch) | |
| tree | c9f6ffa2005dc259fab2730cf40d2e719b09118b /hw/ppc | |
| parent | 715c54071a43ab978dc12b9da22a5016203ed284 (diff) | |
pseries: Add helper to calculate recommended hash page table size
At present we calculate the recommended hash page table (HPT) size for a
pseries guest just once in ppc_spapr_init() before allocating the HPT.
In future patches we're going to want this calculation in other places, so
this splits it out into a helper function. While we're at it, change the
calculation to use ctz() instead of an explicit loop.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Diffstat (limited to 'hw/ppc')
| -rw-r--r-- | hw/ppc/spapr.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index c3157154e0..2a81e8f8a9 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -1050,6 +1050,19 @@ static void close_htab_fd(sPAPRMachineState *spapr) spapr->htab_fd = -1; } +static int spapr_hpt_shift_for_ramsize(uint64_t ramsize) +{ + int shift; + + /* We aim for a hash table of size 1/128 the size of RAM (rounded + * up). The PAPR recommendation is actually 1/64 of RAM size, but + * that's much more than is needed for Linux guests */ + shift = ctz64(pow2ceil(ramsize)) - 7; + shift = MAX(shift, 18); /* Minimum architected size */ + shift = MIN(shift, 46); /* Maximum architected size */ + return shift; +} + static void spapr_alloc_htab(sPAPRMachineState *spapr) { long shift; @@ -1790,16 +1803,7 @@ static void ppc_spapr_init(MachineState *machine) /* Setup a load limit for the ramdisk leaving room for SLOF and FDT */ load_limit = MIN(spapr->rma_size, RTAS_MAX_ADDR) - FW_OVERHEAD; - /* We aim for a hash table of size 1/128 the size of RAM. The - * normal rule of thumb is 1/64 the size of RAM, but that's much - * more than needed for the Linux guests we support. */ - spapr->htab_shift = 18; /* Minimum architected size */ - while (spapr->htab_shift <= 46) { - if ((1ULL << (spapr->htab_shift + 7)) >= machine->maxram_size) { - break; - } - spapr->htab_shift++; - } + spapr->htab_shift = spapr_hpt_shift_for_ramsize(machine->maxram_size); spapr_alloc_htab(spapr); /* Set up Interrupt Controller before we create the VCPUs */ |