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8b0b1db013
put_cpu_no_resched() is an optimization of put_cpu() which unfortunately can cause high latencies. The nfs iostats code uses put_cpu_no_resched() in a code sequence where a reschedule request caused by an interrupt between the get_cpu() and the put_cpu_no_resched() can delay the reschedule for at least HZ. The other users of put_cpu_no_resched() optimize correctly in interrupt code, but there is no real harm in using the put_cpu() function which is an alias for preempt_enable(). The extra check of the preemmpt count is not as critical as the potential source of missing a reschedule. Debugged in the preempt-rt tree and verified in mainline. Impact: remove a high latency source [akpm@linux-foundation.org: build fix] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Tony Luck <tony.luck@intel.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/*
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* linux/fs/nfs/iostat.h
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*
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* Declarations for NFS client per-mount statistics
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*
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* Copyright (C) 2005, 2006 Chuck Lever <cel@netapp.com>
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*
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*/
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#ifndef _NFS_IOSTAT
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#define _NFS_IOSTAT
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#include <linux/percpu.h>
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#include <linux/cache.h>
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#include <linux/nfs_iostat.h>
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struct nfs_iostats {
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unsigned long long bytes[__NFSIOS_BYTESMAX];
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#ifdef CONFIG_NFS_FSCACHE
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unsigned long long fscache[__NFSIOS_FSCACHEMAX];
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#endif
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unsigned long events[__NFSIOS_COUNTSMAX];
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} ____cacheline_aligned;
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static inline void nfs_inc_server_stats(const struct nfs_server *server,
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enum nfs_stat_eventcounters stat)
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{
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struct nfs_iostats *iostats;
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int cpu;
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cpu = get_cpu();
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iostats = per_cpu_ptr(server->io_stats, cpu);
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iostats->events[stat]++;
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put_cpu();
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}
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static inline void nfs_inc_stats(const struct inode *inode,
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enum nfs_stat_eventcounters stat)
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{
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nfs_inc_server_stats(NFS_SERVER(inode), stat);
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}
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static inline void nfs_add_server_stats(const struct nfs_server *server,
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enum nfs_stat_bytecounters stat,
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unsigned long addend)
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{
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struct nfs_iostats *iostats;
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int cpu;
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cpu = get_cpu();
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iostats = per_cpu_ptr(server->io_stats, cpu);
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iostats->bytes[stat] += addend;
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put_cpu();
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}
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static inline void nfs_add_stats(const struct inode *inode,
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enum nfs_stat_bytecounters stat,
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unsigned long addend)
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{
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nfs_add_server_stats(NFS_SERVER(inode), stat, addend);
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}
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#ifdef CONFIG_NFS_FSCACHE
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static inline void nfs_add_fscache_stats(struct inode *inode,
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enum nfs_stat_fscachecounters stat,
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unsigned long addend)
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{
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struct nfs_iostats *iostats;
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int cpu;
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cpu = get_cpu();
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iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
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iostats->fscache[stat] += addend;
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put_cpu();
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}
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#endif
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static inline struct nfs_iostats *nfs_alloc_iostats(void)
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{
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return alloc_percpu(struct nfs_iostats);
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}
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static inline void nfs_free_iostats(struct nfs_iostats *stats)
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{
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if (stats != NULL)
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free_percpu(stats);
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}
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#endif /* _NFS_IOSTAT */
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