Joined: 02 Jan 2017
|Posted: Tue Aug 06, 2019 10:55 pm Post subject: Difference between ramdisk and hard disk compilation
|After seeing a post on compilation speed when it comes to ramdisk and standard hard disk I decided to make my own test. To that end I used the command time sudo emerge chromium, both the tmp file being on a hard disk and when on a tmpfs ramdisk. I found that when using modern hardware, having a ramdisk doesn't really change that much when it comes to compilation times. You can see the results before.
Without ramdisk: sudo emerge chromium 107611.12s user 4386.16s system 1097% cpu 2:50:05.91 total
With ramdisk: sudo emerge chromium 107604.42s user 4606.26s system 1121% cpu 2:46:41.09 total
smartctl 7.0 2018-12-30 r4883 [x86_64-linux-5.1.21-gentoo] (local build)
Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Toshiba 2.5" HDD MK..59GSXP (AF)
Device Model: TOSHIBA MK3259GSXP
Serial Number: 22N5C8C7T
LU WWN Device Id: 5 000039 3d350c188
Firmware Version: GN003J
User Capacity: 320,072,933,376 bytes [320 GB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 2.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ATA8-ACS (minor revision not indicated)
SATA Version is: SATA 2.6, 3.0 Gb/s (current: 3.0 Gb/s)
Local Time is: Tue Aug 6 17:49:23 2019 CDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status: (0x00) Offline data collection activity
was never started.
Auto Offline Data Collection: Disabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
Total time to complete Offline
data collection: ( 120) seconds.
Offline data collection
capabilities: (0x5b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
Offline surface scan supported.
No Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 2) minutes.
Extended self-test routine
recommended polling time: ( 103) minutes.
SCT capabilities: (0x003d) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000b 100 100 050 Pre-fail Always - 0
2 Throughput_Performance 0x0005 100 100 050 Pre-fail Offline - 0
3 Spin_Up_Time 0x0027 100 100 001 Pre-fail Always - 1206
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 4496
5 Reallocated_Sector_Ct 0x0033 100 100 050 Pre-fail Always - 0
7 Seek_Error_Rate 0x000b 100 100 050 Pre-fail Always - 0
8 Seek_Time_Performance 0x0005 100 100 050 Pre-fail Offline - 0
9 Power_On_Hours 0x0032 053 053 000 Old_age Always - 18863
10 Spin_Retry_Count 0x0033 189 100 030 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 2776
191 G-Sense_Error_Rate 0x0032 100 100 000 Old_age Always - 107
192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age Always - 103
193 Load_Cycle_Count 0x0032 008 008 000 Old_age Always - 923449
194 Temperature_Celsius 0x0022 100 100 000 Old_age Always - 29 (Min/Max 14/44)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
220 Disk_Shift 0x0002 100 100 000 Old_age Always - 67
222 Loaded_Hours 0x0032 077 077 000 Old_age Always - 9244
223 Load_Retry_Count 0x0032 100 100 000 Old_age Always - 0
224 Load_Friction 0x0022 100 100 000 Old_age Always - 0
226 Load-in_Time 0x0026 100 100 000 Old_age Always - 349
240 Head_Flying_Hours 0x0001 100 100 001 Pre-fail Offline - 0
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
No self-tests have been logged. [To run self-tests, use: smartctl -t]
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
As you can see, even with a much older 5400 rpm hard drive there isn't any time difference between a ramdisk compilation and a ramdiskless compilation.
Joined: 01 Nov 2005
|Posted: Tue Aug 06, 2019 11:32 pm Post subject:
|linux file cache and it probably also depends on the filesystem used for the tmp and the number of jobs in MAKEOPTS="-j4"
typically emerge will extract a tar containing sources in a tmp dir and start compiling if there is enough memory in the systems the files will be still in the file cache in memory and will not be read from disk during compilation.
I emerged with /var/tmp on a iscsi disk over the network to save flash cycles on the eMMC andit wasn't teribly slower.
True ignorance is not the absence of knowledge, but the refusal to acquire it.
Ab esse ad posse valet, a posse ad esse non valet consequentia
My fediverse account: @firstname.lastname@example.org
Joined: 05 Jul 2003
Location: 56N 3W
|Posted: Wed Aug 07, 2019 8:08 pm Post subject:
Like erm67 says, if you have the RAM to compile in tmpfs, there are little or no speed gains.
However, it does save writes that will never be read.
That's a very good thing if you worry about your SSD failing before you were going to replace it anyway.
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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