I want to limit the number of threads I create based on the amount of free physical memory. For instance I want to stop making new threads once I reach the point that there is only 7GB of real memory left. How would I do so?
You can use Devices.ComputerInfo to get the total amount of free physical memory:
Dim info = New Microsoft.VisualBasic.Devices.ComputerInfo()
Dim gb = info.AvailablePhysicalMemory / 1024 / 1024 / 1024
While gb >= 7
' start your threads here ... '
gb = info.AvailablePhysicalMemory / 1024 / 1024 / 1024
End While
Related
I'm learning OpenCL/CUDA for GPU computing.
When I study the GDDR5 architecture, I'm told that
memory bus = quntity of memory channel * memory channel width
I see an AMD GPU has 16 memory channels with 32-bits wide, so I get the memory pin width = 16 * 32 = 512bits.
But I found that the mainstream graphic card has only 256/384-bits memory bus.
What's going wrong with it?
For GPUs, the number of memory channels usually is not explicitely stated, but rather the total bus width (in bits) for all channels combined. The bus width varies greatly depending on how many memory modules are on the PCB and the bus width per memory module. GPUs with 256bit total bus width typically have 8 memory modules with 1GB capacity each and GPUs with 384bit have 12.
For CPUs or integrated GPUs which share main memory:
memory bus width per channel = 64bit
numer of memory channels = 2 (mainstream plattforms) / 4 or 8 (high-end desktop / workstation)
memory clock = 1600MHz (DDR3) - 3200+MHz (DDR4)
memory bandwidth = 0.125 * memory bus width per channel * numer of memory channels * memory clock
For dedicated GPUs:
total memory bus width = 64bit (GDDR3) - 256bit (GDDR5) - 5120bit (HBM2)
effective memory clock = <5GHz (GDDR5) - 19.5GHz (GDDR6X)
memory bandwidth = 0.125 * total memory bus width * effective memory clock
As you can see in the below command I have assigned a total of 500 GB disk space to my VM. But I am seeing 14.4 GB actual space available to the disk and once it gets used completely. I got an error there isn't much space to use? How to extend space for /dev/mapper/centos-root.
I am using VMware ESXi and using centOS for this VM.
[root#localhost Apr]# fdisk -l
Disk /dev/sda: 536.9 GB, 536870912000 bytes, 1048576000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x00064efd
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
Disk /dev/mapper/centos-root: 14.4 GB, 14382268416 bytes, 28090368 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1719 MB, 1719664640 bytes, 3358720 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 byte
Execute bellow Steps to increase your Linux Disk after adding space in VMWare :
Step 1 - update partition table
fdisk /dev/sda
Press p to print the partition table to identify the number of partitions.
Press n to create a new primary partition.
Press p for primary.
Press 3 for the partition number, depending on the output of the partition table print.
Press Enter two times.
Press t to change the system's partition ID.
Press 3 to select the newly creation partition.
Type 8e to change the Hex Code of the partition for Linux LVM.
Press w to write the changes to the partition table.
Step 2 - Restart the virtual machine.
Step 3 - verify that the changes were saved
fdisk -l
Step 4 - convert the new partition to a physical volume
pvcreate /dev/sda3
Step 5 - extend the physical volume (centos is your VG name, if not use your VG name in place of centos )
vgextend centos /dev/sda3
Step 6 - extend the Logical Volume (500G is the size you want to add , if not use the right size in place of 500G)
lvextend -L+500G /dev/mapper/centos-root
Step 7 - expand the ext filesystem online
resize2fs /dev/mapper/centos-root
extend disk without reboot
echo 1 > /sys/block/sda/device/rescan
echo 1 > /sys/block/sdb/device/rescan
echo 1 > /sys/block/nvme0n1/device/rescan_controller
partprobe
gdisk fix warnging
parted change partion size
## parted can executed as command line. but this is very dangerous
parted -s /dev/sdb "resizepart 2 -1" quit
parted -s /dev/sdb "resizepart 3 100%" quit
resizepart 3 100%
pvresize /dev/sda3
lvextend -l +100%FREE cs/root
xfs_growfs /dev/cs/root
Good morning, this is what i get from apache error
Fatal Error Unable to allocate shared memory segment of 134217728 bytes: mmap: Cannot allocate memory (12)
This is my ipcs -lm
------ Limiti della memoria condivisa --------
max number of segments = 4096
max seg size (kbytes) = 131072
max total shared memory (kbytes) = 536870912
dimensione min seg (byte) = 1
This is cat /etc/sysctl.conf
# Controls the default maxmimum size of a mesage queue
# kernel.msgmnb = 65536
# Controls the maximum size of a message, in bytes
# kernel.msgmax = 65536
# Controls the maximum shared segment size, in bytes
# kernel.shmmax = 200000000
# Controls the maximum number of shared memory segments, in pages
# kernel.shmall = 50000
#
I've set unlimit to unlimited, and i've tryed all the things present on internet.
Can you please tell me what's wrong?
first of all,
please consider to remove # sign before
# kernel.shmmax = 200000000
# kernel.shmall = 50000
like this:
# Controls the maximum shared segment size, in bytes
kernel.shmmax = 200000000
# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 50000
If I am not wrong, than with triple indirect addressing, the maximum file size for ext3 would be (4G+4M+4K).
Likewise, what will be the the maximum file size for an ext4 FS using extents if we assume a 4KB disk block size?
BS = Block size = 4 KiB
You missed the 12 direct pointers in your calculation for ext3:
(12*BS = 48 KiB) + 4 MiB + 4 GiB + 4 TiB
For ext4, we use 32-bit indexing for the extents:
2^32 * (BS = 2^12) = 2^44 = 16 TiB
which is the number you would e.g. also find on Wikipedia for the maximum ext4 file size.
My kernel archive 100% utilization, but the kernel time is at only 3% and there is no time overlap between memory copies and kernels.
Especially the high utilization and the low kernel time don't make sense to me.
So how should I proceed in optimizing my kernel?
I already made sure, that I only have coalesced and pinned memory access, like the profiler recommended.
`Quadro FX 580 utilization = 100.00% (62117.00/62117.00)`
Kernel time = 3.05 % of total GPU time
Memory copy time = 0.9 % of total GPU time
Kernel taking maximum time = Pinned (0.7% of total GPU time)
Memory copy taking maximum time = memcpyHtoD (0.5% of total GPU time)
There is no time overlap between memory copies and kernels on GPU
Furtermore I have no warp serialization, no divergent branches, and no occupancy limiting factor.
Kernel details: Grid size: [4 1 1], Block size: [256 1 1]
Register Ratio: 0.9375 ( 7680 / 8192 ) [10 registers per thread]
Shared Memory Ratio: 0.09375 ( 1536 / 16384 ) [60 bytes per Block]
Active Blocks per SM: 3 (Maximum Active Blocks per SM: 8)
Active threads per SM: 768 (Maximum Active threads per SM: 768)
Potential Occupancy: 1 ( 24 / 24 )
Achieved occupancy: 0.333333 (on 4 SMs)
Occupancy limiting factor: None
p.s. I don't claim that I wrote wundercode, but I just don't know how to proceed from here.
it seems the grid size of your kernel is too small to make full use of SM.
why not decrease block size and increase the grid size.
i think it will do some help.