Re: RBD persistent writeback cache crash (was: performance)

Hi, So I've been doing some tests with v16.2.4 with a 2TB Samsung PM983 SSD mounted under /mnt/rbd-cache rbd_persistent_cache_mode = ssd rbd_persistent_cache_size = 2G rbd_persistent_cache_path = /mnt/rbd-cache rbd_plugins = pwl_cache I tried both XFS and EXT4 as the filesystem. This however leads to fio or 'rbd bench' to crash: root@infra-138-b16-27:~# fio fio/rbd_rw_1.fio rbd_w_iodepth_1: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=rbd, iodepth=1 fio-3.1 Starting 1 process Segmentation fault1)][13.3%][r=0KiB/s,w=14.7MiB/s][r=0,w=3768 IOPS][eta 00m:52s] root@infra-138-b16-27:~# (The IOps seem great!) My fio test is fairly simple: [global] ioengine=rbd clientname=admin pool=rbd rbdname=fio1 invalidate=0 bs=4k runtime=60 direct=1 [rbd_w_iodepth_1] rw=randwrite iodepth=1 I have tried to trace it with gdb, but I didn't get further with my backtrace then: (gdb) bt #0 ContextWQ::process (ctx=0x7fffb8081480, this=0x7fffb8012470) at ./src/common/WorkQueue.h:556 #1 ThreadPool::PointerWQ<Context>::_void_process (this=0x7fffb8012470, item=0x7fffb8081480, handle=...) at ./src/common/WorkQueue.h:341 #2 0x00007fffec600912 in ThreadPool::worker (this=0x7fffb8012018, wt=<optimized out>) at ./src/common/WorkQueue.cc:117 #3 0x00007fffec601801 in ThreadPool::WorkThread::entry (this=<optimized out>) at ./src/common/WorkQueue.h:395 #4 0x00007ffff5c796db in start_thread (arg=0x7fffb17fa700) at pthread_create.c:463 #5 0x00007ffff579e71f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Has anybody been able to use pwl_cache successfully?