Messages in this thread Patch in this message | | | Date | Mon, 7 Mar 2011 17:23:09 +0530 | From | Kamalesh Babulal <> | Subject | [PATCH 5/7] powerpc/kexec: Speedup kexec hash PTE tear down |
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powerpc/kexec: Speedup kexec hash PTE tear down
Commit: d504bed676caad29a3dba3d3727298c560628f5c upstream
Currently for kexec the PTE tear down on 1TB segment systems normally requires 3 hcalls for each PTE removal. On a machine with 32GB of memory it can take around a minute to remove all the PTEs.
This optimises the path so that we only remove PTEs that are valid. It also uses the read 4 PTEs at once HCALL. For the common case where a PTEs is invalid in a 1TB segment, this turns the 3 HCALLs per PTE down to 1 HCALL per 4 PTEs.
This gives an > 10x speedup in kexec times on PHYP, taking a 32GB machine from around 1 minute down to a few seconds.
Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Kamalesh babulal <kamalesh@linux.vnet.ibm.com> cc: Anton Blanchard <anton@samba.org> --- arch/powerpc/platforms/pseries/lpar.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-)
Index: b/arch/powerpc/platforms/pseries/lpar.c =================================================================== --- a/arch/powerpc/platforms/pseries/lpar.c 2011-03-07 00:50:53.695992154 -0800 +++ b/arch/powerpc/platforms/pseries/lpar.c 2011-03-07 02:09:06.133815481 -0800 @@ -366,21 +366,28 @@ { unsigned long size_bytes = 1UL << ppc64_pft_size; unsigned long hpte_count = size_bytes >> 4; - unsigned long dummy1, dummy2, dword0; + struct { + unsigned long pteh; + unsigned long ptel; + } ptes[4]; long lpar_rc; - int i; + int i, j;
- /* TODO: Use bulk call */ - for (i = 0; i < hpte_count; i++) { - /* dont remove HPTEs with VRMA mappings */ - lpar_rc = plpar_pte_remove_raw(H_ANDCOND, i, HPTE_V_1TB_SEG, - &dummy1, &dummy2); - if (lpar_rc == H_NOT_FOUND) { - lpar_rc = plpar_pte_read_raw(0, i, &dword0, &dummy1); - if (!lpar_rc && ((dword0 & HPTE_V_VRMA_MASK) - != HPTE_V_VRMA_MASK)) - /* Can be hpte for 1TB Seg. So remove it */ - plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2); + /* Read in batches of 4, + * invalidate only valid entries not in the VRMA + * hpte_count will be a multiple of 4 + */ + for (i = 0; i < hpte_count; i += 4) { + lpar_rc = plpar_pte_read_4_raw(0, i, (void *)ptes); + if (lpar_rc != H_SUCCESS) + continue; + for (j = 0; j < 4; j++) { + if ((ptes[j].pteh & HPTE_V_VRMA_MASK) == + HPTE_V_VRMA_MASK) + continue; + if (ptes[j].pteh & HPTE_V_VALID) + plpar_pte_remove_raw(0, i + j, 0, + &(ptes[j].pteh), &(ptes[j].ptel)); } } }
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