Messages in this thread | | | Date | Thu, 29 Jun 2023 18:54:27 -0700 | Subject | Re: [PATCH v1 11/14] arm64/mm: Wire up PTE_CONT for user mappings | From | John Hubbard <> |
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On 6/22/23 07:42, Ryan Roberts wrote: > With the ptep API sufficiently refactored, we can now introduce a new > "contpte" API layer, which transparently manages the PTE_CONT bit for > user mappings. Whenever it detects a set of PTEs that meet the > requirements for a contiguous range, the PTEs are re-painted with the > PTE_CONT bit. > > This initial change provides a baseline that can be optimized in future > commits. That said, fold/unfold operations (which imply tlb > invalidation) are avoided where possible with a few tricks for > access/dirty bit management. > > Write-enable and write-protect modifications are likely non-optimal and > likely incure a regression in fork() performance. This will be addressed > separately. > > Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> > ---
Hi Ryan!
While trying out the full series from your gitlab features/granule_perf/all branch, I found it necessary to EXPORT a symbol in order to build this. Please see below:
... > + > +pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte) > +{ > + /* > + * Gather access/dirty bits, which may be populated in any of the ptes > + * of the contig range. We are guarranteed to be holding the PTL, so any > + * contiguous range cannot be unfolded or otherwise modified under our > + * feet. > + */ > + > + pte_t pte; > + int i; > + > + ptep = contpte_align_down(ptep); > + > + for (i = 0; i < CONT_PTES; i++, ptep++) { > + pte = __ptep_get(ptep); > + > + /* > + * Deal with the partial contpte_ptep_get_and_clear_full() case, > + * where some of the ptes in the range may be cleared but others > + * are still to do. See contpte_ptep_get_and_clear_full(). > + */ > + if (pte_val(pte) == 0) > + continue; > + > + if (pte_dirty(pte)) > + orig_pte = pte_mkdirty(orig_pte); > + > + if (pte_young(pte)) > + orig_pte = pte_mkyoung(orig_pte); > + } > + > + return orig_pte; > +}
Here we need something like this, in order to get it to build in all possible configurations:
EXPORT_SYMBOL_GPL(contpte_ptep_get);
(and a corresponding "#include linux/export.h" at the top of the file).
Because, the static inline functions invoke this routine, above.
thanks, -- John Hubbard NVIDIA
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