On 9/28/2018 6:15 PM, Junio C Hamano wrote:
Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx> writes:
if (!nr) {
ieot_blocks = istate->cache_nr / THREAD_COST;
- if (ieot_blocks < 1)
- ieot_blocks = 1;
cpus = online_cpus();
if (ieot_blocks > cpus - 1)
ieot_blocks = cpus - 1;
So, am I reading this correctly - you need cpus > 2 before an
IEOT extension block is written out?
OK.
Why should we be even calling online_cpus() in this codepath to
write the index in a single thread to begin with?
The number of cpus that readers would use to read this index file
has nothing to do with the number of cpus available to this
particular writer process.
As I mentioned in my other reply, this is optimizing for the most common
case where the index is read from the same machine that wrote it and the
user is taking the default settings (ie index.threads=true).
Aligning the number of blocks to the number of threads that will be
processing them avoids situations where one thread may have up to double
the work to do as the other threads (for example, if there were 3 blocks
to be processed by 2 threads).
