On Sat, Apr 16, 2016 at 3:21 AM, David Turner <dturner@xxxxxxxxxxxxxxxx> wrote:
> On Fri, 2016-04-15 at 18:25 +0700, Duy Nguyen wrote:
>> On Thu, Apr 14, 2016 at 1:47 AM, David Turner <
>> dturner@xxxxxxxxxxxxxxxx> wrote:
>> > > > + fd = unix_stream_connect(socket_path);
>> > > > + if (refresh_cache) {
>> > > > + ret = write_in_full(fd, "refresh", 8) != 8;
>> > >
>> > > Since we've moved to unix socket and had bidirectional
>> > > communication,
>> > > it's probably a good idea to read an "ok" back, giving index
>> > > -helper
>> > > time to prepare the cache. As I recall the last discussion with
>> > > Johannes, missing a cache here when the index is around 300MB
>> > > could
>> > > hurt more than wait patiently once and have it ready next time.
>> >
>> > It is somewhat slower to wait for the daemon (which requires a disk
>> > load + a memcpy) than it is to just load it ourselves (which is
>> > just a
>> > disk load).
>>
>> You forgot the most costly part, SHA-1 verification. For very large
>> index, I assume the index-helper is already in the middle of hashing
>> the index content. If you ignore index-helper, you need to go hash
>> the
>> whole thing again. The index-helper can hand it to you if you wait
>> just a bit more. This wait time should be shorter because index
>> -helper
>> is already in the middle of hashing (and in optimistic case, very
>> close to finishing it).
>
> You're right -- I did forget that part.
>
> In "index-helper: use watchman to avoid refreshing index with lstat()",
> we switch from just poking to poking and waiting for a reply. Then in
> "read-cache: config for waiting for index-helper", we make that waiting
> optional. So what if I just remove that patch? Does that solve it?
>
Yes. I think so.
--
Duy
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