Changeset 587e31a in trunk
- Timestamp:
- 2011-05-08T12:42:28Z (14 years ago)
- Branches:
- master
- Children:
- 3eb60ff9
- Parents:
- 3dc4917
- File:
-
- 1 edited
-
docs/performance.rst (modified) (12 diffs)
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TabularUnified docs/performance.rst ¶
r3dc4917 r587e31a 48 48 network: ~N 49 49 50 memory footprint: N/K*S50 memory footprint: S 51 51 52 52 when the file is not already uploaded … … 63 63 cpu: 2*~A 64 64 65 network: ~N + ~A65 network: N/K*A 66 66 67 67 memory footprint: N/K*S … … 70 70 ===================================== 71 71 72 cpu: ~A + a large constant for RSA keypair generation 73 72 74 network: A 73 75 74 76 memory footprint: N/K*A 75 76 cpu: ~A + a large constant for RSA keypair generation77 77 78 78 notes: Tahoe-LAFS generates a new RSA keypair for each mutable file that it … … 87 87 ======================================================= 88 88 89 cpu: ~B 90 89 91 network: B 90 91 cpu: ~A92 92 93 93 notes: When Tahoe-LAFS 1.8.0 or later is asked to read an arbitrary … … 102 102 ===================================================== 103 103 104 cpu: ~A 105 104 106 network: A 105 107 … … 112 114 Modifying ``B`` bytes of an ``A``-byte mutable file 113 115 =================================================== 116 117 cpu: ~A 114 118 115 119 network: A … … 127 131 Inserting/Removing ``B`` bytes in an ``A``-byte mutable file 128 132 ============================================================ 133 134 cpu: ~A 129 135 130 136 network: A … … 145 151 =========================================== 146 152 153 cpu: ~A 154 147 155 network: ~A 148 156 149 memory footprint: N/K* A157 memory footprint: N/K*~A 150 158 151 159 notes: In Tahoe-LAFS, directories are implemented as specialized mutable … … 156 164 ================================ 157 165 166 cpu: ~A 167 158 168 network: ~A 159 169 160 memory footprint: N/K* A170 memory footprint: N/K*~A 161 171 162 172 notes: Listing a directory requires that the mutable file storing the … … 168 178 ============================================= 169 179 170 network: ~G, where G is the number of servers on your grid 180 cpu: ~G 181 182 network: ~G 171 183 172 184 memory footprint: negligible … … 180 192 ============================================== 181 193 194 cpu: ~N/K*A 195 182 196 network: N/K*A 183 197 … … 185 199 186 200 notes: To verify a file, Tahoe-LAFS downloads all of the ciphertext 187 shares that were originally uploaded to the grid and integrity 188 checks them. This is, for well-behaved grids, likely to be more 189 expensive than downloading an A-byte file, since only a fraction 190 of these shares are necessary torecover the file.201 shares that were originally uploaded to the grid and integrity checks 202 them. This is (for well-behaved grids) more expensive than downloading 203 an A-byte file, since only a fraction of these shares are necessary to 204 recover the file. 191 205 192 206 Repairing an ``A``-byte file (mutable or immutable) 193 207 =================================================== 194 208 195 network: variable; up to around ~A 196 197 memory footprint: from S to (1+N/K)*S 198 199 notes: To repair a file, Tahoe-LAFS downloads the file, and generates/uploads 200 missing shares in the same way as when it initially uploads the file. 201 So, depending on how many shares are missing, this can be about as 202 expensive as initially uploading the file in the first place. 209 cpu: variable, between ~A and ~N/K*A 210 211 network: variable; between A and N/K*A 212 213 memory footprint: (1+N/K)*S 214 215 notes: To repair a file, Tahoe-LAFS downloads the file, and 216 generates/uploads missing shares in the same way as when it initially 217 uploads the file. So, depending on how many shares are missing, this 218 can cost as little as a download or as much as a download followed by 219 a full upload.
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