cvs commit: src/sys/compat/linux linux_file.c src/sys/compat/svr4 svr4_filio.c src/sys/dev/streams streams.c src/sys/fs/devfs devfs_vnops.c src/sys/fs/fdescfs fdesc_vfsops.c fdesc_vnops.c src/sys/fs/fifofs fifo_vnops.c src/sys/fs/unionfs union_subr.c ...

[Robert Watson]

rwatson     2007-04-04 09:11:34 UTC

  FreeBSD src repository

  Modified files:
    sys/compat/linux     linux_file.c 
    sys/compat/svr4      svr4_filio.c 
    sys/dev/streams      streams.c 
    sys/fs/devfs         devfs_vnops.c 
    sys/fs/fdescfs       fdesc_vfsops.c fdesc_vnops.c 
    sys/fs/fifofs        fifo_vnops.c 
    sys/fs/unionfs       union_subr.c 
    sys/kern             kern_descrip.c kern_event.c kern_fork.c 
                         subr_witness.c sys_generic.c 
                         uipc_mqueue.c uipc_syscalls.c 
                         uipc_usrreq.c vfs_cache.c vfs_lookup.c 
                         vfs_mount.c vfs_syscalls.c 
    sys/netsmb           smb_dev.c 
    sys/opencrypto       cryptodev.c 
    sys/security/audit   audit_bsm_klib.c 
    sys/sys              filedesc.h 
  Log:
  Replace custom file descriptor array sleep lock constructed using a mutex
  and flags with an sxlock.  This leads to a significant and measurable
  performance improvement as a result of access to shared locking for
  frequent lookup operations, reduced general overhead, and reduced overhead
  in the event of contention.  All of these are imported for threaded
  applications where simultaneous access to a shared file descriptor array
  occurs frequently.  Kris has reported 2x-4x transaction rate improvements
  on 8-core MySQL benchmarks; smaller improvements can be expected for many
  workloads as a result of reduced overhead.
  
  - Generally eliminate the distinction between "fast" and regular
    acquisisition of the filedesc lock; the plan is that they will now all
    be fast.  Change all locking instances to either shared or exclusive
    locks.
  
  - Correct a bug (pointed out by kib) in fdfree() where previously msleep()
    was called without the mutex held; sx_sleep() is now always called with
    the sxlock held exclusively.
  
  - Universally hold the struct file lock over changes to struct file,
    rather than the filedesc lock or no lock.  Always update the f_ops
    field last. A further memory barrier is required here in the future
    (discussed with jhb).
  
  - Improve locking and reference management in linux_at(), which fails to
    properly acquire vnode references before using vnode pointers.  Annotate
    improper use of vn_fullpath(), which will be replaced at a future date.
  
  In fcntl(), we conservatively acquire an exclusive lock, even though in
  some cases a shared lock may be sufficient, which should be revisited.
  The dropping of the filedesc lock in fdgrowtable() is no longer required
  as the sxlock can be held over the sleep operation; we should consider
  removing that (pointed out by attilio).
  
  Tested by:      kris
  Discussed with: jhb, kris, attilio, jeff
  
  Revision  Changes    Path
  1.103     +17 -4     src/sys/compat/linux/linux_file.c
  1.35      +4 -4      src/sys/compat/svr4/svr4_filio.c
  1.55      +2 -2      src/sys/dev/streams/streams.c
  1.143     +3 -1      src/sys/fs/devfs/devfs_vnops.c
  1.56      +2 -2      src/sys/fs/fdescfs/fdesc_vfsops.c
  1.104     +5 -5      src/sys/fs/fdescfs/fdesc_vnops.c
  1.136     +3 -1      src/sys/fs/fifofs/fifo_vnops.c
  1.91      +2 -2      src/sys/fs/unionfs/union_subr.c
  1.307     +174 -170  src/sys/kern/kern_descrip.c
  1.109     +9 -9      src/sys/kern/kern_event.c
  1.270     +2 -2      src/sys/kern/kern_fork.c
  1.228     +0 -2      src/sys/kern/subr_witness.c
  1.155     +11 -12    src/sys/kern/sys_generic.c
  1.21      +10 -11    src/sys/kern/uipc_mqueue.c
  1.250     +14 -9     src/sys/kern/uipc_syscalls.c
  1.201     +10 -9     src/sys/kern/uipc_usrreq.c
  1.108     +4 -4      src/sys/kern/vfs_cache.c
  1.100     +2 -2      src/sys/kern/vfs_lookup.c
  1.252     +2 -2      src/sys/kern/vfs_mount.c
  1.436     +26 -25    src/sys/kern/vfs_syscalls.c
  1.32      +3 -3      src/sys/netsmb/smb_dev.c
  1.33      +3 -1      src/sys/opencrypto/cryptodev.c
  1.6       +2 -2      src/sys/security/audit/audit_bsm_klib.c
  1.76      +15 -61    src/sys/sys/filedesc.h