Re: [PATCH v3 0/2] Hugetlbfs support for riscv

[Alexandre Ghiti <alex@ghiti.fr>]

On 7/4/19 12:57 AM, Paul Walmsley wrote:
> Hi Alex,
>
> Thanks for writing and testing these patches, and thanks for your patience
> waiting for reviews and testing.


No problem :)


> On Mon, 1 Jul 2019, Alexandre Ghiti wrote:
>
>> This series introduces hugetlbfs support for both riscv 32/64. Riscv32
>> is architecturally limited to huge pages of size 4MB whereas riscv64 has
>> 2MB/1G huge pages support. Transparent huge page support is not
>> implemented here, I will submit another series later.
>>                                                                                   
> [ ... ]
>
>> This series was validated using libhugetlbfs testsuite ported to riscv64
>> without linker script support.
>> (https://github.com/AlexGhiti/libhugetlbfs.git, branch dev/alex/riscv).
>>                                                                                   
>> - libhugetlbfs testsuite on riscv64/2M:
>>    - brk_near_huge triggers an assert in malloc.c, does not on x86.
> I was able to reproduce the 2MB megapages test results on rv64 QEMU.  On a
> HiFive Unleashed, though, a few more tests fail:
>
> - icache_hygiene fails ("icache unclean")
>
>    # LD_LIBRARY_PATH=obj64 ./tests/obj64/icache-hygiene
>    Starting testcase "./tests/obj64/icache-hygiene", pid 732
>    SIGILL at 0x15559fff80 (sig_expected=0x15559fff80)
>    SIGILL at 0x1555dfff80 (sig_expected=0x1555dfff80)
>    SIGILL at 0x15561fff80 (sig_expected=0x15561fff80)
>    SIGILL at 0x15565fff80 (sig_expected=0x15565fff80)
>    SIGILL at 0x15569fff80 (sig_expected=0x15569fff80)
>    SIGILL at 0x1556dfff80 (sig_expected=(nil))
>    FAIL   SIGILL somewhere unexpected
>    #
>
> - One of the heapshrink tests fails ("Heap did not shrink")
>
>    # LD_PRELOAD="obj64/libhugetlbfs_privutils.so obj64/libhugetlbfs.so tests/obj64/libheapshrink.so" HUGETLB_MORECORE_SHRINK=yes HUGETLB_MORECORE=yes tests/obj64/heapshrink
>    Starting testcase "tests/obj64/heapshrink", pid 753
>    FAIL    Heap did not shrink
>    #
>
> Some of these may be related to the top-down mmap work, but there might be
> more work to do on actual hardware.


I don't think this is related to top-down mmap layout, this test only 
mmaps a huge page.
It might be interesting to see more verbose messages adding 
HUGETLB_VERBOSE=99
when launching the test.


>
>> - libhugetlbfs testsuite on riscv64/1G:
>>    - brk_near_huge triggers an assert in malloc.c, does not on x86.
>>    - mmap-gettest, mmap-cow: testsuite passes the number of default free
>>      pages as parameters and then fails for 1G which is not the default.
>>      Otherwise succeeds when given the right number of pages.
>>    - map_high_truncate_2 fails on x86 too: 0x60000000 is not 1G aligned
>>      and fails at line 694 of fs/hugetlbfs/inode.c.
>>    - heapshrink on 1G fails on x86 too, not investigated.
>>    - counters.sh on 1G fails on x86 too: alloc_surplus_huge_page returns
>>      NULL in case of gigantic pages.
>>    - icache-hygiene succeeds after patch #3 of this series which lowers
>>      the base address of mmap.
>>    - fallocate_stress.sh on 1G never ends, on x86 too, not investigated.
> I can reproduce some of these here on QEMU.  But for reasons that are
> unclear to me, 1G gigapages aren't working on the HiFive Unleashed here.
>
> In any case, these patches are clearly a good start, so I've queued
> them for v5.3.
>
>
> - Paul
>
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