Messages in this thread | | | Date | Wed, 14 Sep 2005 15:17:01 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] reorder struct files_struct |
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Dipankar Sarma <dipankar@in.ibm.com> wrote: > > > --- linux-2.6.14-rc1/include/linux/file.h 2005-09-13 05:12:09.000000000 +0200 > > +++ linux-2.6.14-rc1-ed/include/linux/file.h 2005-09-15 01:09:13.000000000 +0200 > > @@ -34,12 +34,12 @@ > > */ > > struct files_struct { > > atomic_t count; > > - spinlock_t file_lock; /* Protects all the below members. Nests inside tsk->alloc_lock */ > > struct fdtable *fdt; > > struct fdtable fdtab; > > fd_set close_on_exec_init; > > fd_set open_fds_init; > > struct file * fd_array[NR_OPEN_DEFAULT]; > > + spinlock_t file_lock; /* Protects concurrent writers. Nests inside tsk->alloc_lock */ > > }; > > > > #define files_fdtable(files) (rcu_dereference((files)->fdt)) > > For most apps without too many open fds, the embedded fd_sets > are going to be used. Wouldn't that mean that open()/close() will > invalidate the cache line containing fdt, fdtab by updating > the fd_sets ? If so, you optimization really doesn't help.
Guys, this is benchmarkable. fget() is astonishingly high in some profiles - it's worth investigating. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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