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Revision 33323f21117e5bb8cf72569302f109aabb387bb9 authored by Mark Callaghan on 14 September 2012, 19:35:02 UTC, committed by Mark Callaghan on 14 September 2012, 23:43:50 UTC 
Remove use of mmap for random reads
 
Summary:
Reads via mmap on concurrent workloads are much slower than pread.
For example on a 24-core server with storage that can do 100k IOPS or more
I can get no more than 10k IOPS with mmap reads and 32+ threads.

Test Plan: db_bench benchmarks

Reviewers: dhruba, heyongqiang

Reviewed By: heyongqiang

Differential Revision: https://reviews.facebook.net/D5433
1 parent fa29f82
Raw File
db_iter.h 
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef STORAGE_LEVELDB_DB_DB_ITER_H_
#define STORAGE_LEVELDB_DB_DB_ITER_H_

#include <stdint.h>
#include "leveldb/db.h"
#include "db/dbformat.h"

namespace leveldb {

// Return a new iterator that converts internal keys (yielded by
// "*internal_iter") that were live at the specified "sequence" number
// into appropriate user keys.
extern Iterator* NewDBIterator(
    const std::string* dbname,
    Env* env,
    const Comparator* user_key_comparator,
    Iterator* internal_iter,
    const SequenceNumber& sequence);

}  // namespace leveldb

#endif  // STORAGE_LEVELDB_DB_DB_ITER_H_
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