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[Qemu-devel] [PULL 05/26] pseries: Add helper to calculate recommended h
From: |
David Gibson |
Subject: |
[Qemu-devel] [PULL 05/26] pseries: Add helper to calculate recommended hash page table size |
Date: |
Thu, 18 Feb 2016 15:18:26 +1100 |
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 <address@hidden>
Reviewed-by: Alexey Kardashevskiy <address@hidden>
---
hw/ppc/spapr.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index c315715..2a81e8f 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 */
--
2.5.0
- [Qemu-devel] [PULL 08/26] migration: ensure htab_save_first completes after timeout, (continued)
- [Qemu-devel] [PULL 08/26] migration: ensure htab_save_first completes after timeout, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 25/26] pseries: Include missing pseries-2.5 compat properties in pseries-2.4, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 14/26] cuda: port AUTOPOLL command to new framework, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 19/26] cuda: port FILE_SERVER_FLAG command to new framework, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 24/26] cuda: remove CUDA_GET_SET_IIC/CUDA_COMBINED_FORMAT_IIC commands, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 18/26] cuda: port RESET_SYSTEM command to new framework, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 06/26] pseries: Move hash page table allocation to reset time, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 22/26] cuda: port SET_TIME command to new framework, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 26/26] hw/ppc/spapr: Halt CPU when powering off via RTAS call, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 04/26] pseries: Simplify handling of the hash page table fd, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 05/26] pseries: Add helper to calculate recommended hash page table size,
David Gibson <=
- [Qemu-devel] [PULL 23/26] cuda: remove GET_6805_ADDR command, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 20/26] cuda: port SET_POWER_MESSAGES command to new framework, David Gibson, 2016/02/17
- [Qemu-devel] [PULL 11/26] hw/ppc/spapr: Implement the h_set_xdabr hypercall, David Gibson, 2016/02/17
- Re: [Qemu-devel] [PULL 00/26] ppc-for-2.6 queue 20160218, Peter Maydell, 2016/02/18