| 1 | SPDX-License-Identifier: CC-BY-SA-4.0 |
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| 2 | active: true |
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| 3 | appl-config-option-data-type: | |
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| 4 | Boolean feature macro. |
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| 5 | appl-config-option-default-value: | |
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| 6 | The default IMFS block size is 128 bytes. |
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| 7 | appl-config-option-description: | |
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| 8 | This configuration parameter specifies the block size for in-memory files |
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| 9 | managed by the IMFS. The configured block size has two impacts. The first |
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| 10 | is the average amount of unused memory in the last block of each file. For |
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| 11 | example, when the block size is 512, on average one-half of the last block |
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| 12 | of each file will remain unused and the memory is wasted. In contrast, when |
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| 13 | the block size is 16, the average unused memory per file is only 8 |
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| 14 | bytes. However, it requires more allocations for the same size file and |
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| 15 | thus more overhead per block for the dynamic memory management. |
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| 16 | |
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| 17 | Second, the block size has an impact on the maximum size file that can be |
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| 18 | stored in the IMFS. With smaller block size, the maximum file size is |
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| 19 | correspondingly smaller. The following shows the maximum file size possible |
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| 20 | based on the configured block size: |
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| 21 | |
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| 22 | - when the block size is 16 bytes, the maximum file size is 1,328 bytes. |
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| 23 | |
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| 24 | - when the block size is 32 bytes, the maximum file size is 18,656 bytes. |
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| 25 | |
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| 26 | - when the block size is 64 bytes, the maximum file size is 279,488 bytes. |
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| 27 | |
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| 28 | - when the block size is 128 bytes, the maximum file size is 4,329,344 bytes. |
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| 29 | |
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| 30 | - when the block size is 256 bytes, the maximum file size is 68,173,568 bytes. |
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| 31 | |
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| 32 | - when the block size is 512 bytes, the maximum file size is 1,082,195,456 |
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| 33 | bytes. |
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| 34 | appl-config-option-index: [] |
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| 35 | appl-config-option-name: CONFIGURE_IMFS_MEMFILE_BYTES_PER_BLOCK |
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| 36 | appl-config-option-notes: | |
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| 37 | None. |
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| 38 | appl-config-option-range: | |
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| 39 | Valid values for this configuration parameter are a power of two (2) |
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| 40 | between 16 and 512 inclusive. In other words, valid values are 16, 32, 64, |
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| 41 | 128, 256,and 512. |
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| 42 | copyrights: |
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| 43 | - Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) |
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| 44 | derived: false |
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| 45 | enabled-by: [] |
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| 46 | header: '' |
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| 47 | interface-type: appl-config-option |
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| 48 | level: 1.64 |
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| 49 | links: |
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| 50 | - RTEMS-ACFG-FILESYSTEM: 9RfguldyRuN5UR-zcLUoiTYBDzow1fnI4B_ZnP_UyKk= |
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| 51 | normative: true |
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| 52 | ref: '' |
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| 53 | reviewed: iA2QqUff1w3cWEYU5hSqcvelHFH2rdGHHEb8TCVHTdQ= |
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| 54 | text: '' |
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| 55 | type: interface |
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