From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: linux-mm@kvack.org
Cc: linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Will Deacon <will@kernel.org>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nick Piggin <npiggin@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vineet Gupta <Vineet.Gupta1@synopsys.com>
Subject: [RFC] asm-generic/tlb: stub out pmd_free_tlb() if __PAGETABLE_PMD_FOLDED
Date: Fri, 11 Oct 2019 15:38:18 -0700 [thread overview]
Message-ID: <20191011223818.7238-1-vgupta@synopsys.com> (raw)
In-Reply-To: <20191011121951.nxna6hruuskvdxod@box>
This is inine with similar patches for nopud [1] and nop4d [2] cases.
However I'm not really sure I understand clearly how the nopmd code is
supposed to work (for a 2 tier paging system) - hence the RFC.
Consider free_pmd_range() simplified/annotated below
free_pmd_range
...
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) => *pmd_bad()/pmd_clear_bad() [a]*
continue;
free_pte_range(tlb, pmd, addr);
} while (pmd++, addr = next, addr != end);
...
*pmd_free_tlb(tlb, pmd, start); => [b]*
For ARC/nopmd case [a] is actually checking pgd and consequently
pmd_clear_bad() can't be stubbed out for PMD_FOLDED case. However it seems
case [b] can be stubbed out (hence this patch) along same lines as [1] and [2]
| bloat-o-meter2 vmlinux-E-elide-p?d_clear_bad vmlinux-F-elide-pmd_free_tlb
| add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-112 (-112)
| function old new delta
| free_pgd_range 422 310 -112
| Total: Before=4137002, After=4136890, chg -1.000000%
[1] http://lists.infradead.org/pipermail/linux-snps-arc/2019-October/006266.html
[2] http://lists.infradead.org/pipermail/linux-snps-arc/2019-October/006265.html
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
include/asm-generic/tlb.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index f3dad87f4ecc..a1edad7d4170 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -574,6 +574,7 @@ static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vm
} while (0)
#endif
+#ifndef __PAGETABLE_PMD_FOLDED
#ifndef pmd_free_tlb
#define pmd_free_tlb(tlb, pmdp, address) \
do { \
@@ -583,6 +584,9 @@ static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vm
__pmd_free_tlb(tlb, pmdp, address); \
} while (0)
#endif
+#else
+#define pmd_free_tlb(tlb, pmdp, address) do { } while (0)
+#endif
#ifndef __PAGETABLE_PUD_FOLDED
#ifndef pud_free_tlb
--
2.20.1
next prev parent reply other threads:[~2019-10-11 22:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 22:26 [PATCH 0/3] eldie generated code for folded p4d/pud Vineet Gupta
2019-10-09 22:26 ` [PATCH 1/3] asm-generic/tlb: stub out pud_free_tlb() if __PAGETABLE_PUD_FOLDED Vineet Gupta
2019-10-09 22:26 ` [PATCH 2/3] asm-generic/tlb: stub out p4d_free_tlb() if __PAGETABLE_P4D_FOLDED Vineet Gupta
2019-10-09 22:26 ` [PATCH 3/3] asm-generic/mm: stub out p{4,d}d_clear_bad() if __PAGETABLE_P{4,u}D_FOLDED Vineet Gupta
2019-10-10 7:29 ` [PATCH 0/3] eldie generated code for folded p4d/pud Peter Zijlstra
2019-10-10 8:56 ` Kirill A. Shutemov
2019-10-10 20:05 ` Vineet Gupta
2019-10-11 12:19 ` Kirill A. Shutemov
2019-10-11 22:38 ` Vineet Gupta [this message]
2019-10-14 17:41 ` [RFC] asm-generic/tlb: stub out pmd_free_tlb() if __PAGETABLE_PMD_FOLDED Linus Torvalds
2019-10-14 18:02 ` Vineet Gupta
2019-10-14 18:25 ` Linus Torvalds
2019-10-14 19:08 ` Vineet Gupta
2019-10-14 20:38 ` Linus Torvalds
2019-10-14 21:48 ` Matthew Wilcox
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191011223818.7238-1-vgupta@synopsys.com \
--to=vineet.gupta1@synopsys.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=arnd@arndb.de \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=torvalds@linux-foundation.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).