pcstat syscall mincore failed with bad address if file is larger than 512MB on arm64 4K_PAGES machines

[baiyz]

System: Ubuntu 16.04 LTS on Cavium 48core ARMv8 ThunderX1 Linux thunderx1 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:05:42 UTC 2016 aarch64 aarch64 aarch64 GNU/Linux

pcstat failed if file is larger than 512MB. Our page size was 4096, however pcstat used 65536. pcstat also calculated the wrong page count on arm64 system.

Test 1: pcstat /var/lib/cassandra/data/keyspace1/standard1-19ce2110716e11e7843f219b546b9b42/test +-----------------------------------------------------------------------------------+----------------+------------+-----------+---------+ | Name | Size (bytes) | Pages | Cached | Percent | |-----------------------------------------------------------------------------------+----------------+------------+-----------+---------| | /var/lib/cassandra/data/keyspace1/standard1-19ce2110716e11e7843f219b546b9b42/test | 525107053 | 8013 | 8013 | 100.000 | +-----------------------------------------------------------------------------------+----------------+------------+-----------+---------+

Test 2: cat mc-69-big-Data.db >> test

pcstat /var/lib/cassandra/data/keyspace1/standard1-19ce2110716e11e7843f219b546b9b42/test 2017/08/08 13:08:14 skipping "/var/lib/cassandra/data/keyspace1/standard1-19ce2110716e11e7843f219b546b9b42/test": syscall SYS_MINCORE failed: bad address +-------+----------------+------------+-----------+---------+ | Name | Size (bytes) | Pages | Cached | Percent | |-------+----------------+------------+-----------+---------| +-------+----------------+------------+-----------+---------+

ls -l /var/lib/cassandra/data/keyspace1/standard1-19ce2110716e11e7843f219b546b9b42 -rw-r--r-- 1 root root 599909718 Aug 8 13:08 test

getconf PAGE_SIZE 4096

cat /proc/meminfo MemTotal: 32929196 kB MemFree: 184936 kB MemAvailable: 19768376 kB Buffers: 87476 kB Cached: 19477888 kB SwapCached: 0 kB Active: 5676236 kB Inactive: 15960632 kB Active(anon): 2092140 kB Inactive(anon): 8664 kB Active(file): 3584096 kB Inactive(file): 15951968 kB Unevictable: 9921816 kB Mlocked: 9921816 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 4 kB Writeback: 0 kB AnonPages: 11993340 kB Mapped: 11821268 kB Shmem: 9284 kB Slab: 423280 kB SReclaimable: 340060 kB SUnreclaim: 83220 kB KernelStack: 18416 kB PageTables: 279516 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 16464596 kB Committed_AS: 15227224 kB VmallocTotal: 133142937536 kB VmallocUsed: 0 kB VmallocChunk: 0 kB AnonHugePages: 9535488 kB CmaTotal: 0 kB CmaFree: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB

[baiyz]

golang.org hardcode arm64 pagesize to 65536, which may not be correct

golang.org/x/sys/unix/syscall_linux_arm64.go:func Getpagesize() int { return 65536 }

[baiyz]

golang 1.9 fixed page size problem, however, pcstat cannot be built under golang 1.9 (arm64)

[tobert]

Hey! Sorry about the delay. I'll take a look at cross-compiling and figuring this out soon. I have a Pine64 board here somewhere too so I can test.